This just in:

There's a report of a man with a rifle in the Administration Bldg. UAPD is on the scene. Please stay away from the area.
— Univ. of Arizona (@UofA) March 23, 2013

Update: Just spoke with UAPD. No further information at this time, and there's been no confirmation that there was a shooting — they're looking into the report.

We'll keep things updated as we hear about them.

Update: Scanner reports say that there is "no indication that UMC is in any danger."

Interesting development. UA campus is on lockdown cause there's a man w/ a rifle on campus. We just got locked in the Rec Room till its over
— Jason Harris (@jrharris22) March 23, 2013

Update, 5:46 p.m.: Scanner reports saying that there's a male subject on the third floor of the Admin building, on the north side.

Update, 5:54 p.m.: From UAalert campus alert system: "Leave Admin bldg NOW thru 2nd fl lobby out the north lobby doors UAPD in bldg"

Update, 5:56 p.m.: From UAalert: "Evacuate Modern Languages Bldg to the east exits. Leave now thru the east doors"

Update: 5:59 p.m.: TPD scanner chatter: UA evacuees "haven't seen or heard anything out of the ordinary."

Update 6:07 p.m.: From UAalert: "UAPD & TPD are searching the Admin Bldg. remain clear of the area around Admin Bldg."

Update 7:20 p.m.: From UAalert: "Investigation continues at Admin Bldg. Avoid areas around Admin Bldg, 2nd St and Mountain due to police activity." Floor-by-floor sweeps have turned up nothing so far.

Update 7:29 p.m.: From UAalert: "The campus is open EXCEPT for the administration bldg during this on-going investigation." Sweeps are continuing.

Update 8:41 p.m.: Via @DailyWildcat: Police appear to be leaving campus. We're calling it a night here. If any more information comes in, we'll keep you updated.