Story highlights NASCAR veteran Jason Leffler had just returned to dirt-track racing 
 
 He died Wednesday in a crash at a New Jersey dirt track 
 
 NASCAR calls Leffler a "fierce competitor" who will be missed 
 
 "Lost a good guy tonight," racer Bobby Labonte tweets 
 
 A violent crash on a dirt track in New Jersey has claimed the life of race car driver Jason Leffler, a NASCAR veteran lauded by fellow racers as a fierce and versatile competitor. 
 
 Leffler, 37, died Wednesday, a little more than three months after returning to the world of short-track open-wheel racing after focusing on NASCAR circuits for more than a decade, according to his website. 
 
 "Sitting here in disbelief. ... All I can think about is Charlie," NASCAR racer Elliott Sadler said, referring to Leffler's 5-year-old son. 
 
 Leffler's death at Bridgeport Speedway in Swedesboro, New Jersey, came during a qualifying race during the Night of Wings event, a 25-lap race for sprint cars equipped with stabilizing wings. 
 
 Sprint cars are high-powered cars that usually run on dirt or paved oval tracks. 
 
 JUST WATCHED Remembering NASCAR's Jason Leffler Replay More Videos ... MUST WATCH Remembering NASCAR's Jason Leffler 04:35 
 
 Leffler was on the fourth turn of the preliminary heat when his car left the banked dirt track and flipped several times down the front straightaway, the South Jersey Times newspaper reported , citing witnesses. 
 
 He had to be pulled from the vehicle, the newspaper said. 
 
 "NASCAR extends its thoughts, prayers and deepest sympathies to the family of Jason Leffler who passed away earlier this evening," NASCAR said Wednesday in a statement . "For more than a decade, Jason was a fierce competitor in our sport and he will be missed." 
 
 Condolences poured in from fellow drivers. 
 
 "Lost a good guy tonight in Jason Leffler. Prayers with your family!" racer Bobby Labonte said in a Twitter post. 
 
 "My thoughts and prayers are with Jason's family and friends," driver Jeff Burton posted . "Breaks my heart thinking of his little boy." 
 
 Leffler began racing when was 12 years old, according to his website, and went on to win four U.S. Auto Club racing championships -- including three back-to-back championships from 1997 to 1999 -- and a place in the National Midget Auto Racing Hall of Fame. 
 
 In 2000, he finished 17th in the Indianapolis 500. 
 
 He switched his racing focus that same year to NASCAR's Nationwide Series and later to the Camping World Truck Series in 2002, according to his website. 
 
 The Long Beach, California, native won two Nationwide Series races and finished in the top 10 in points for six consecutive years, according to his website. 
 
 He decided to return to dirt racing for 2013, planning to compete in up to 65 sprint car races. 
 
 "I've got a lot of learning to do," he was quoted as saying on his website in March. "It's cool to be able to race 3 times a week and figure things out." 
 
 Sprint car racing can be a dangerous sport, and accidents are not infrequent. 
 
 A 22-year-old driver died three weeks ago in a crash at Bloomington Speedway in Monroe County, Indiana, CNN affiliate WTHR reported. 
 
 In March, two spectators died when a car veered off-track at Marysville Raceway Park, outside Sacramento, California. 
 
 In that incident, a car hit two tractor tires, sending it airborne and striking two spectators, a 68-year-old man and a 14-year-old boy. The driver was uninjured. ||||| Jason Leffler, shown here on July 21, 2012, won two Nationwide races and one Truck Series race in his NASCAR career. (Photo: Tyler Barrick, Getty Images for NASCAR) 
 
 Jason Leffler, a versatile driver who won championships in open-wheel divisions and attempted at least one full season in each of NASCAR's three national series, died Wednesday night after a crash in a 410 sprint car race at Bridgeport Speedway in New Jersey. 
 
 Leffler, 37, was pronounced dead shortly after 9 p.m., the New Jersey State Police said. Sgt. Adam Grossman told USA TODAY Sports that Leffler had to be extricated from the car after striking a wall around 8:30 p.m. He was transported to Crozer-Chester Medical Center, where he was pronounced dead. 
 
 He was running in second place in the first heat race of the program at the 0.625-mile, high-banked dirt oval when his car flipped several times on the front straightaway, according to eyewitness Chris Taitt, 40, of West Deptford, N.J. Taitt said Leffler's car hit the wall twice and "then it was flopping all over." 
 
 After state police arrived on the scene, the track announced the rest of the races had been canceled. 
 
 Leffler made 73 starts in the Sprint Cup Series, finishing last in his final event after completing eight laps Sunday at Pocono Raceway. He won twice in the Nationwide Series and once in the Camping World Truck Series. 
 
 The Long Beach, Calif., native, who was affectionately known as "LEFturn" and had the nickname stenciled above his driver's side window, leaves behind a 5-year-old son, Charlie. 
 
 Jason Leffler's car after a wreck Wednesday night during a sprint car race at the Bridgeport Speedway dirt track in New Jersey. (Photo: Christopher Taitt via @ChristopheTaitt) 
 
 Leffler started his career as an open-wheel star who won three consecutive USAC Midget championships from 1997-99. Following the path of former USAC star Tony Stewart, he signed with Joe Gibbs Racing for the Nationwide Series in 2000. 
 
 After finishing 20th in points with three pole positions and four top 10s in his rookie season, Leffler moved into NASCAR's premier Cup Series with Chip Ganassi Racing. He lasted only one year after failing to qualify for five of 36 races in 2001. 
 
 Leffler moved to the Camping World Truck Series for two years, scoring his first NASCAR national series victory at Dover International Speedway in 2003. He began dabbling in Cup again, making 10 starts for Haas CNC Racing that season. 
 
 In 2004, he earned his first Nationwide Series win and scored 17 top 10s in 27 starts with Haas CNC. 
 
 That earned him his second shot at Cup in 2005 as Joe Gibbs Racing expanded to a third car with FedEx sponsorship. Leffler, though, didn't last the season, being fired by the team after 21 races when he was ranked 35th in points and had failed to qualify for the Coca-Cola 600. Denny Hamlin took over the No. 11 car late in the season. 
 
 Leffler raced full time in Nationwide from 2006-11, earning his final national series win at Indianapolis Raceway Park in 2007 when he finished a career-high third in points. 
 
 He made 11 starts in Sprint Cup over the past six seasons. 
 
 A statement from NASCAR said the sanctioning body "extends its thoughts, prayers and deepest sympathies to the family of Jason Leffler who passed away earlier this evening. For more than a decade, Jason was a fierce competitor in our sport and he will be missed." 
 
 "We are very saddened at the passing of Jason Leffler," Indianapolis Motor Speedway chief operating officer Doug Boles said in a statement. "He was one of the most versatile race drivers in America, showing his talent by competing in the Indianapolis 500 and the Brickyard 400. Jason was a terrific guy who always had time for everyone. Our deepest sympathies are extended to his entire family, team and fans." 
 
 Leffler raced in the Indianapolis 500 in 2000 and the Brickyard 400 in 2001, 2003-05 and '08. 
 
 PHOTOS: Remembering Jason Leffler
– NASCAR driver Jason Leffler, 37, died yesterday in a racing crash, CNN reports. Leffler was driving in "Night of Wings," a New Jersey sprint car race not sponsored by NASCAR. His car flipped multiple times and hit a wall twice, a witness tells USA Today. He'd been in second place. He was taken to a nearby hospital, where he was pronounced dead. "For more than a decade, Jason was a fierce competitor in our sport and he will be missed," NASCAR said in a statement.