The lockdown at Davis-Monthan Air Force Base ended Friday afternoon with officials saying no gunman or weapon was found in a search of a building on the grounds.
Col. John Cherrey made a statement to journalists gathered outside the base at 6 p.m. praising the effort to make sure people on base were safe and announcing the end of the lockdown. But he did not answer questions about the incident that spanned the entire day and tied up police, fire and other emergency responders for hours following reports that a man armed with a gun had holed up in on of the building on the sprawling facility stretching across the city's southeast side.
A SWAT team, hostage negotiators and a bomb unit are still on scene but Tucson police said about 4 p.m. that the situation had been "normalized."
The FBI sent agents from its Tucson and Phoenix offices at the scene of the situation at Davis Monthan, said spokesman Manuel Johnson. The FBI is not in a lead role, but rather assisting, he said.
University Medical Center was put on trauma alert, and Tucson police and fire crews responded to the base en masse, in some cases with their lights and sirens going.
Earlier today, a report of a possible gunman on the base prompted the lockdown, Sgt. Russ Martin said this afternoon. Base officials remained tight-lipped about the situation, but reports of a barricaded man on the premises were confirmed late this afternoon by various officials and was reported by media outlets across the country.
Mike Hein, director of emergency management for Pima County, said his office was apprised of the situation by the Pima County Sheriff's Department as a courtesy and was not "directly involved" in it. He was kept apprised through a liaison, but mostly from news releases, Hein said.
A TUSD school on the base, Borman Elementary, and a charter school there, Sonoran Science Academy, were also put on lockdown. That caused some parents to go to the gates of the base to try to get their children. Many waited for hours for instructions on how to get their children off the base.