( CNN ) -- U.S. Air Force officials called off their response late Friday afternoon at a Tucson , Arizona , base after reports that an armed man had entered an office building , the U.S. military branch said in a statement . Earlier in the day , a U.S. military official told CNN that a gunman was believed to be holed up in a building at the Davis-Monthan Air Force Base . This precipitated the Air Force to call for a lock-down -- which began at 10:30 a.m. -- `` following the unconfirmed sighting of '' such a man . No shots were ever fired and law enforcement teams are on site , said the official , who had direct knowledge of the situation from conversations with base officials but did not want to be identified . In fact , at 6 p.m. , Col. John Cherrey -- who commands the Air Force 's 355th Fighter Wing -- told reporters that no gunman or weapon was ever found . He added that the building , where the gunman was once thought to have entered , has been secured after authorities went through it room-by-room . The announcement came about two hours after the Air Force stated that its officials had `` terminated '' their response to the incident . All base personnel were leaving via a `` controlled release . '' `` With the help of the Tucson emergency services communities , Airmen were successful in maintaining the safety and security of the Desert Lightning Team , '' the Air Force said , alluding to the name used for Air Force personnel based in the arid southern Arizona locale . Earlier , Tucson Police Sgt . Maria Hawke said in an e-mailed statement that members of the department 's SWAT team , hostage unit and bomb squad are near the site on a `` stand-by '' basis in case they are needed . But she said that they are `` not actively engaged in any enforcement , investigative or other activity . '' And Manuel Johnson , a Phoenix-based spokesman for the FBI , added that some agency personnel have been dispatched to the base to help , if needed . Shortly before noon Friday , Staff Sgt . Caitlyn Jones confirmed that there was a security situation at the base and that it was on lock-down mode . `` It has been reduced to a single point of entry , '' she said . Borman Elementary School , which is located inside the base , was put on lock down at 11 a.m. , said Karen Bynum , executive assistant to the Tucson school district 's superintendent . Its 501 students were confined to their classrooms , with all perimeter doors locked . But shortly after 4 p.m. , off-base parents were allowed onto the base to pick up students at the school and Sonoran Science Academy , according to a statement from the Air Force . On-base parents were told to `` take the most direct route '' to locations where their children may be . The incident occurs nearly two years after 13 people were killed in a shooting spree at the Fort Hood army base in Texas . CNN 's Barbara Starr , Terry Frieden , Tina Burnside and Alta Spells contributed to this report .
NEW : An Air Force official says no gunman was found and the site is `` secure '' The lock down was initiated hours earlier after `` unconfirmed sightings '' of an armed man . FBI agents , along with Tucson police , were dispatched to the Arizona air base to help . No shots were fired and no one was hurt , a U.S. military official says .