Around midday the base posted this message on its Facebook page: "Davis-Monthan AFB is responding to a unconfirmed report of an individual with a weapon. Local agencies are engaged per standard operating procedures."
SWAT vehicles could be seen entering the base. Activity appeared to be concentrated in a structure identified as building 4300, said to be an old dorm building now used for Civil Engineering.
A helicopter crew from KGUN9 news partner KNXV-TV of Phoenix observed a file of several people wearing SWAT-style military clothing approaching the building early in the afternoon. The chopper was flying about five miles outside the base, and was using a telephoto lens to see the action..
The Arizona Republic, citing an unnamed source, reported Friday afternoon that SWAT was negotiating with an armed man holed up in the building. According to the Republic, there were no hostages and no shots had been fired.
But whatever is causing the lockdown, the situation still had not been resolved as of 4:10 PM Tucson time. The base was providing no further information. Nor was the Tucson Police Department returning calls or responding to emails from KGUN9 News.
The first indication that someone was up at the base came just before 11:00 AM, when the KGUN9 News desk began receiving calls from people who said they were on lockdown inside the base. Some of the callers said they'd heard an official announcement saying that a shooter or shooters had fired shots in the Civil Engineering building. One caller said she was inside the BX grocery store on base when an announcement came over the PA stating that the store's doors were being locked because of reports that a man was on base armed with an AK 47. Other callers told similar stories.
D-M Building 4300. Courtesy KNXV.-TV.
Personnel clad in SWAT type gear approach building 4300. Courtesy KNXV
Detail from helicopter photo of SWAT-style personnel approaching building 4300