Tucson's Davis-Monthan Air Force Base on lockdownTUCSON -- Davis-Monthan Air Force Base in Arizona is on lockdown, but a spokeswoman at the Tucson base would release few details other than no one was being allowed in or out of the base.A Tucson television news station, KVOA, reported on Twitter that the Tucson Fire Department was responding to Davis-Monthan for a possible patient with gunshot wounds.Air Force Staff Sgt. Caitlin Jones refused to tell The Associated Press why the base was on lockdown.The base is best known as the boneyard for old military and government airplanes.Ron Barber, who was there for a commemoration ceremony for POWs and MIAs, left the base as the lockdown started at 10 a.m. Security at the base directed traffic outward. He did not hear any gunshots. They did not tell him why they were locking down the base.Base spokeswoman says she can't confirm details at this time but that the base has been "reduced to a single point entry because of a potential security situation," and officials are currently investigating. She says that's the same as a lockdown.The Pima Air & Space Museum south of the base remains open, but public tours that it does on the base have been canceled, officials said. At least two schools, Borman Elementary of Tucson Unified School District and Sonoran Science Academy, arer on lockdown.