It appears to be the Rayburn Office Building. All staff have been ordered to "shelter in place"
Here's the first AP report...
WASHINGTON (AP) - Police sealed off the Capitol on Friday after receiving reports of gunfire in a House office building across the street.
Capitol police are investigating "the sound of gunfire in the garage level of the Rayburn House Office Building," said an announcement on the internal Capitol voice alarm system.
The Senate was in session at the time, but the House was not. Rep. Peter Hoekstra, R-Mich., conducting a House Intelligence Committee hearing, interrupted a witness to request those attending the meeting to remain in the room and said the doors must be closed.
"It's a little unsettling to get a Blackberry message put in front of you that says there's gunfire in the building," he said.
Update (paul) After 90 minutes of it looking like a false alarm, FoxNews is reporting that they have reports that someone with a gun was apprehended. -- But details are so sketchy you can't put too much stock in that. -- Reuters is reporting they are RE-locking down the Capitol after lifting it. Sounds like something is up.
Cap Police Presser: Reports of shots fired, no suspects, NO INJURIES. -- If I can paraphrase, "We got a phone call of shots fired and we're checking it out." -- SINGLE report. Maybe it is much ado about nothing.
I'll say this, (from the TV) it looks like the Cap police are ALL OVER this thing.
Cap police presser says Reuters wrong (above) Capitol open. Fox is running they have a report that 2 women reported a guy with a gun in a staff gym. Potentially apprehended. More questions than answers.
Update (Kim): Catherine Herridge of Fox is reporting that the Capitol Hill news conference has been moved back from 1:15 to 1:30pm
Update (Kim): Rep. Jack Kingston issued a statement saying that the woman who was taken to the hospital was a member of his staff. She was not injured but was "shaken up" by everything that has happened.
(Paul) For those of you following this by internet..... What apparently is going on is that they are searching every room in the massive building. That takes time. Almost 3 hours into this we still are basically in a holding patern.
3:23pm All Clear is sounded. Apparently the whole thing was a false alarm from an anonymous phone call. FAR FAR be it from me to call this an "over-reaction" but it seems like we should try to find a better way to handle things like this.
3:55pm (Kim) Kimberly Schneider of the Capitol Hill Police reports that construction workers working in the basement of the Rayburn Building made the loud sounds that the anonymous caller, referenced above, said sounded like gunfire.