A police car is parked outside the Josef-Koenig-Gymnasium high school in Haltern am See, March, 24, 2015. 
 
 A police tape is stretched outside the Josef-Koenig-Gymnasium high school in Haltern am See, March, 24, 2015. 
 
 Students gather in front of lit candles outside the Josef-Koenig-Gymnasium high school in Haltern am See, March, 24, 2015. 
 
 Lit candles are placed outside the Josef-Koenig-Gymnasium high school in Haltern am See, March, 24, 2015. The text reads: 'In silent sympathy.' 
 
 Students embrace in front of lit candles outside the Josef-Koenig-Gymnasium high school in Haltern am See, March, 24, 2015. 
 
 HALTERN AM SEE, Germany Students and teachers at a small-town German high school broke down in tears once they realized that 16 classmates and two teachers were on board an ill-fated Germanwings airplane that crashed in France on Tuesday on a flight to Duesseldorf. 
 
 The 10th grade students from the Joseph-Koenig-Gymnasium high school were on their way home after a week-long Spanish exchange program at the Institut Giola in Llinars del Vallès near Barcelona. It was a reciprocal visit after 12 Spanish students had spent a week at their school in December. 
 
 "It was a Spanish language exchange program and they were flying home after having what was probably the most wonderful time of their lives," said Sylvia Loehrmann, the education minister for the state of North Rhine-Westphalia. 
 
 "It's so tragic, so sad, so unfathomable," she said. Most of the students were about 15 years old. 
 
 The Airbus operated by Lufthansa's Germanwings budget airline crashed in the French Alps, killing all 150 on board. Germanwings confirmed its flight from Barcelona to Duesseldorf went down with 144 passengers and six crew. 
 
 Haltern am See mayor Bodo Klimpel said that word spread quickly through the school about reports that a plane from Barcelona had gone missing and the students began researching on their own to try to find out more about the plane's fate. 
 
 "And then when the plane didn't land and they were unable to make contact with their friends and classmates by cell phone, that's when they assumed the worst had happened," said the mayor, who was also fighting off tears at a news conference. 
 
 "The students were informed that there was a sufficient probability that the plane would not be landing in Duesseldorf," Klimpel said. "Classes were then called off." 
 
 CANDLES AND TEARS 
 
 The students were sent home but many returned in the afternoon with candles in their hands and tears in their eyes to mourn with each other at the school. 
 
 "It's the darkest day in this town's history," said Klimpel, who added some parents nevertheless drove to the airport and some to the school. "We're in a state of shock. It's the worst thing ever imaginable." 
 
 He said the school would be opened on Wednesday but there wouldn't be any normal lessons. "It'll be a chance for the students to talk about the horrible thing that happened." 
 
 The town lies about 30 km (20 miles) to the north of Dortmund and Gelsenkirchen - homes of two major German soccer clubs and former mining towns. It is 50 km (30 miles) north of Duesseldorf. 
 
 Haltern am See's history dates back to 1289 and perhaps its most famous son in soccer player Christoph Metzelder, a former Germany defender who also played for Borussia Dortmund and Real Madrid. Germany defender Benedikt Hoewedes, who plays for Gelsenkirchen's Schalke 04 club, is also from Haltern am See. 
 
 The nearby Sixtus church and another local church opened their doors for students, teachers and local residents to mourn and flags in the town of 37,000 that lies just north of the Ruhr River Valley industrial area were lowered to half-mast. 
 
 The mayor of the Spanish town Llinars del Valles, Marti Pujol, told Reuters that these kinds of exchanges had been organized for several years with German towns including in the Duesseldorf, Cologne and Hamburg areas. Spanish children had spent a week in December in Haltern am See with German families. 
 
 "The whole village is distraught, Pujol said of his town with 9,000 residents. "The families knew each other... The parents had been to see them off at 6 this morning." 
 
 (Additional reporting by Sarah White in Madrid; Writing by Erik Kirschbaum in Berlin; Editing by Giles Elgood) ||||| SEYNE-LES-ALPES, France (AP) — A black box recovered from the scene and pulverized pieces of debris strewn across Alpine mountainsides held clues to what caused a German jetliner to take an unexplained eight-minute dive Tuesday midway through a flight from Spain to Germany, apparently killing all 150 people on board. 
 
 Debris of the Germanwings passenger jet is scattered on the mountain side near Seyne les Alpes, French Alps, Tuesday, March 24, 2015. A Germanwings passenger jet carrying at least 150 people crashed Tuesday... (Associated Press) 
 
 Rescue workers and gendarme gather in Seyne-les-Alpes, French Alps, Tuesday, March 24, 2015, as search-and-rescue teams struggle to reach the remote crash site of Germanwings passenger plane. A Germanwings... (Associated Press) 
 
 Crying people arrive at Barcelona airport in Spain, Tuesday, March 24, 2015. A Germanwings passenger jet carrying 150 people crashed in the French Alps region Tuesday as it traveled from Barcelona to... (Associated Press) 
 
 People comfort each other as they arrive at the Barcelona airport in Spain, Tuesday, March 24, 2015. A Germanwings passenger jet carrying 150 people crashed in the French Alps region as it traveled from... (Associated Press) 
 
 Rescue workers and helicopter stand at La Seyne les Alpes, French Alps, Tuesday, March 24, 2015, as search-and-rescue teams struggle to reach the remote, snow-covered crash site of Germanwings passenger... (Associated Press) 
 
 A rescue helicopter takes off from La Seyne les Alpes, French Alps, Tuesday, March 24, 2015, as search-and-rescue teams struggle to reach the remote, snow-covered crash site of Germanwings passenger plane.... (Associated Press) 
 
 France's President Francois Hollande after giving a speech during a visit at the ìLigue Contre le Cancerî (League Against Cancer), in Paris, Tuesday, March 24, 2015. A passenger jet carrying over 140... (Associated Press) 
 
 A man who appears to have waited for the missing flight 4U 9525 covers his face at the airport in Duesseldorf, Germany, Tuesday, March 24, 2015, after a Germanwings passenger jet carrying more 140 people... (Associated Press) 
 
 Two girls hug in front of the Joseph-Koenig-Gymnasium in Haltern, western Germany Tuesday, March 24, 2015. A Germanwings plane from Barcelona crashed on its way to Duesseldorf over the French alps, 16... (Associated Press) 
 
 A family of people involved in a crashed plane arrives at the Barcelona airport in Spain, Tuesday, March 24, 2015. A Germanwings passenger jet carrying more than 140 people crashed in the French Alps... (Associated Press) 
 
 Rescue workers and helicopters stand at Seyne-les-Alpes, French Alps, Tuesday, March 24, 2015, as search-and-rescue teams struggle to reach the remote, snow-covered crash site of Germanwings passenger... (Associated Press) 
 
 An helicopter takes off at Seyne les Alpes, French Alps, Tuesday, March 24, 2015. A Germanwings passenger jet carrying at least 150 people crashed Tuesday in a snowy, remote section of the French Alps,... (Associated Press) 
 
 Crying people arrive at Barcelona airport in Spain, Tuesday, March 24, 2015. A Germanwings passenger jet carrying 150 people crashed Tuesday in the French Alps region as it traveled from Barcelona to... (Associated Press) 
 
 Crying people arrive at Barcelona airport in Spain, Tuesday, March 24, 2015. A Germanwings passenger jet carrying 150 people crashed Tuesday in the French Alps region as it traveled from Barcelona to... (Associated Press) 
 
 Rescue workers prepare at Seyne-les-Alpes, French Alps, Tuesday, March 24, 2015, as search-and-rescue teams struggle to reach the remote crash site of Germanwings passenger plane. A Germanwings passenger... (Associated Press) 
 
 A rope hangs from a rescue helicopter flying past debris of the Germanwings passenger jet, scattered on the mountainside, near Seyne les Alpes, French Alps, Tuesday, March 24, 2015. A Germanwings passenger... (Associated Press) 
 
 The victims included two babies, two opera singers and 16 German high school students and their teachers returning from an exchange trip to Spain. It was the deadliest crash in France in decades. 
 
 The Airbus A320 operated by Germanwings, a budget subsidiary of Lufthansa, was less than an hour from landing in Duesseldorf on a flight from Barcelona when it unexpectedly went into a rapid descent. The pilots sent out no distress call and had lost radio contact with their control center, France's aviation authority said, deepening the mystery. 
 
 While investigators searched through debris from Flight 9525 on steep and desolate slopes, families across Europe reeled with shock and grief. Sobbing relatives at both airports were led away by airport workers and crisis counselors. 
 
 "The site is a picture of horror. The grief of the families and friends is immeasurable," German Foreign Minister Frank-Walter Steinmeier said after being flown over the crash scene. "We must now stand together. We are united in our great grief." 
 
 It took investigators hours to reach the site, led by mountain guides to the craggy ravine in the southern French Alps, not far from the Italian border and the French Riviera. 
 
 Video shot from a helicopter and aired by BFM TV showed rescuers walking in the crevices of a rocky mountainside scattered with plane parts. Photos of the crash site showed white flecks of debris across a mountain and larger airplane body sections with windows. A helicopter crew that landed briefly in the area saw no signs of life, French officials said. 
 
 "Everything is pulverized. The largest pieces of debris are the size of a small car. No one can access the site from the ground," Gilbert Sauvan, president of the general council, Alpes-de-Haute-Provence, told The Associated Press. 
 
 "This is pretty much the worst thing you can imagine," said Bodo Klimpel, mayor of the German town of Haltern, rent with sorrow after losing 16 tenth graders and their two teachers. 
 
 The White House and the airline chief said there was no sign that terrorism was involved, and German Chancellor Angela Merkel urged reporters not to speculate on the cause. 
 
 "We still don't know much beyond the bare information on the flight, and there should be no speculation on the cause of the crash," she said in Berlin. "All that will be investigated thoroughly." 
 
 Lufthansa Vice President Heike Birlenbach told reporters in Barcelona that for now "we say it is an accident." 
 
 In Washington, the White House said American officials were in contact with their French, Spanish and German counterparts. "There is no indication of a nexus to terrorism at this time," said U.S. National Security Council spokeswoman Bernadette Meehan. 
 
 Merkel, French President Francois Hollande and Spanish Prime Minister Mariano Rajoy were to visit the site Wednesday. 
 
 French Interior Minister Bernard Cazeneuve said a black box had been located at the crash site and "will be immediately investigated." He did not say whether it was the flight data recorder or the cockpit voice recorder. 
 
 The two devices — actually orange boxes designed to survive extreme heat and pressure — should provide investigators with a second-by-second timeline of the plane's flight. 
 
 The voice recorder takes audio feeds from four microphones within the cockpit and records all the conversations between the pilots, air traffic controllers as well as any noises heard in the cockpit. The flight data recorder captures 25 hours' worth of information on the position and condition of almost every major part in a plane. 
 
 Germanwings is low-cost carrier owned by Lufthansa, Germany's biggest airline, and serves mostly European destinations. Tuesday's crash was its first involving passenger deaths since it began operating in 2002. The Germanwings logo, normally maroon and yellow, was blacked out on its Twitter feed. 
 
 Lufthansa CEO Carsten Spohr called it the "blackest day of our company's 60-year history." He insisted, however, that flying "remains after this terrible day the safest mode of transport." 
 
 Germanwings said 144 passengers and six crew members were on board. Authorities said 67 Germans were believed among the victims, including the 16 high school students and two opera singers, as well as many Spaniards, two Australians and one person each from the Netherlands, Turkey and Denmark. 
 
 Contralto Maria Radner was returning to Germany with her husband and baby after performing in Wagner's "Siegfried," according to Barcelona's Gran Teatre del Liceu. Bass baritone Oleg Bryjak had appeared in the same opera, according to the opera house in Duesseldorf. 
 
 The plane left Barcelona Airport at 10:01 a.m. and had reached its cruising height of 38,000 feet when it suddenly went into an eight-minute descent to just over 6,000 feet, Germanwings CEO Thomas Winkelmann told reporters in Cologne. 
 
 "We cannot say at the moment why our colleague went into the descent, and so quickly, and without previously consulting air traffic control," said Germanwings' director of flight operations, Stefan-Kenan Scheib. 
 
 At 10:30, the plane lost radio contact with the control center but "never declared a distress alert," Eric Heraud of the French Civil Aviation Authority told the AP. 
 
 The plane crashed at an altitude of about 6,550 feet (2,000 meters) at Meolans-Revels, near the popular ski resort of Pra Loup. The site is 430 miles (700 kilometers) south-southeast of Paris. 
 
 "It was a deafening noise. I thought it was an avalanche, although it sounded slightly different. It was short noise and lasted just a few seconds," Sandrine Boisse, the president of the Pra Loup tourism office, told the AP. 
 
 Authorities faced a long and difficult search-and-recovery operation because of the area's remoteness. The weather, which had been clear earlier in the day, deteriorated Tuesday afternoon, with a chilly rain falling. Snow coated nearby mountaintops. 
 
 French Interior Ministry spokesman Pierre-Henry Brandet said the crash site covered several acres, with thousands of pieces of debris, "which leads us to think the impact must have been extremely violent at very high speed." 
 
 Search operations were suspended overnight and were to resume at daybreak, though about 10 gendarmes remained in the desolate ravine to guard the crash site, authorities said. 
 
 Winkelmann said the pilot, whom he did not name, had more than 10 years' experience working for Germanwings and its parent airline Lufthansa. 
 
 Florian Graenzdoerffer Lufthansa Spokesman for North Rhine Westphalia said the company had to cancel seven flights out of Dusseldorf because a number of crew members felt they were unfit to fly following news of the accident. 
 
 "I can't tell you any details because this is a personal decision and in our business we have an agreement if a crew feels unfit to fly ... then we respect this," Graenzdoerffer said. 
 
 The aircraft was delivered to Lufthansa in 1991, had approximately 58,300 flight hours in some 46,700 flights, Airbus said. The plane underwent a routine check in Duesseldorf on Monday, and its last regular full check took place in the summer of 2013. 
 
 The A320 plane is a workhorse of modern aviation, with a good safety record. 
 
 The last time a passenger jet crashed in France was the 2000 Concorde accident, which left 113 dead. 
 
 ___ 
 
 Charlton reported from Paris. Associated Press writers Lori Hinnant, Thomas Adamson and Elaine Ganley in Paris; Claude Paris in Seyne-les-Alpes; David McHugh in Frankfurt; Geir Moulson and David Rising in Berlin; Frank Augstein in Duesseldorf; Al Clendenning in Madrid; Joe Wilson in Barcelona; Kirsten Grieshaber in Haltern, Germany, and AP Airlines writer Scott Mayerowitz in New York contributed to this report.
– As authorities try to figure out why a Germanwings plane went down in the French Alps—there was no distress call before the pilot's eight-minute descent, reports the AP—details are emerging about some of the 150 people aboard who are now presumed dead. That includes 16 kids, all about age 15, who were returning to Germany from a weeklong exchange program in Spain, reports Reuters. They and their two teachers were from the small community of Haltern am See in western Germany, where, as the New York Times notes, many people either knew the victims or were related to them. “This is the darkest day in the history of our city," says Mayor Bodo Klimpel, who was fighting back tears at a news conference. "A feeling of shock can be felt everywhere. It is about the worst thing imaginable." The mayor of Llinars del Valles, where the teens stayed in Spain, says his "whole village is distraught" as well. "The families knew each other," he says. "The parents had been to see them off at 6 this morning." Also on board were two opera singers, Maria Radner and Oleg Bryjak, who were returning from a performance together. Radner was with her husband and baby, and another baby was reportedly killed in the crash.