Early on, it looked ominous when an Air Force base on the southern edge of Tucson was locked down Friday morning amid unconfirmed reports of gunfire. In the end, no shots were fired, and no weapons and gunman were found.
Traffic into the Davis-Monthan Air Force Base was limited as the unspecified security situation was first announced. Schools on the base were locked down. Ambulances and fire engines were rushed to the base, and a TV station reported that emergency workers were responding to a possible patient with multiple gunshot wounds.
This southern Arizona city was already rattled by January's shooting rampage that killed six people and wounded Rep. Gabrielle Giffords and 12 others. And then there was the specter of the 2009 shooting in Texas at Fort Hood.
But, as it turned out, no shots were actually fired. And an ambulance that went to the sprawling base where 6,100 airmen and 1,700 civilians work turned out to be responding to a more conventional call: A woman had gone into labor.
Col. John Cherrey, commander of the base, said officials were satisfied it was safe after a "floor-by-floor, room-by-room" search of the building where a gunman was reported.
"No gunman or weapon was found," Cherrey said. The commander, who held a two-minute news conference to discuss the five-hour lockdown, didn't answer questions from reporters.
Sgt. Maria Hawke, a Tucson police spokeswoman, said base officials told the department that its SWAT, bomb and hostage negotiation squads were no longer needed at the scene. Hawke said she didn't know how the situation was resolved.
Alison Bunnell, who lives at the base with her husband and their four children, was turned away during the lockdown when she tried to return to the base.
Bunnell said she was told that children at the base's schools were oblivious to what was going and were watching movies and eating snacks. She said she wasn't worried.
"We have exercises all the time," Bunnell said.
Davis-Monthan is near the Pima Air & Space Museum and the "boneyard" for old military and government airplanes that is a popular destination for aviation enthusiasts.
The base is the home of the 355th Fighter Wing, and provides attack airpower, combat support and medical forces, according to the base's Facebook page.
Security at military bases has gained more attention in the last two years since an Army major went on a rampage at Fort Hood in Texas in 2009. Maj. Nidal Hasan is charged with 13 counts of premeditated murder and 32 counts of attempted premeditated murder in the shooting spree. Investigators have foiled other plots against military bases in other parts of the country since Sept. 11.
Associated Press writers contributing to this report include Mark Carlson and Jacques Billeaud in Phoenix and Lolita C. Baldor in Washington, D.C.