I’m sure this will turn out to be a car backfiring or something, but Drudge has the siren up so I guess I’m obliged to post. Police have sealed off offices in the Rayburn building and are going room-to-room to investigate.

Standby for details.

Update: Fox News says there’s an AP report of four ambulances arriving at the scene.

Update: Chris Wallace says the FBI terrorism task force is there.

Update: A Congressman interviewed on Fox says there’s no report of anyone being injured, that the ambulances are there as a precautionary measure.

Update: Police allegedly heard the shots and then smelled gunpowder. Someone said on Fox that there’s a firing range down there, but surely the cops would have accounted for that.

Update: Reuters confirms the report of smoke.

Update: FYI, the House is not in session today and most of the staffers have gone home for the Memorial Day weekend.

Update: Fox says staffers got the text message about shots fired a full hour ago, at 10:38.

Update: Fox is reporting now that a gurney is being brought into the building. CNN says there’ll be a press conference at noon.

Update: Duane at Forest for the Trees floats some black humor.

Update: Major Garrett says an announcement was just made in the Rayburn cafeteria that the investigation is continuing and that people in the building should stay where they are and not leave their rooms.

Update: Fox says there’s a report of EMTs running into the Rayburn building. There’s also a report of two women saying they saw a man with a gun. He might have been taken into custody.

Update: Police have re-imposed a lockdown on Capitol Hill after initially lifting it. Meanwhile, Rep. Jack Kingston is live-blogging.

Update: The police spokeswoman says there are tactical units inside the building but they have no info about a gunman.

Update: She says there are no reports of injuries. There’ll be another press conference at 1:15.

Update: The report of the Capitol being locked down again is untrue. It’s open.

Update: Fox is talking about the two women again. Supposedly, they described a white man about 5’10 and 175 lbs. who was hiding in the gym with a gun.

Update (Bryan): Expose the Left has a screen shot of a woman being taken away from the Capitol on a gurney. No obvious injuries apparent, though.

Update: Major Garrett says not only are they not letting people out of the Rayburn building cafeteria, they’re bringing people in — including a pregnant woman. Meanwhile, the latest police news conference reports no suspects or arrests. But the search continues.

Update: Fox reports that they’re starting to let people out of the Rayburn building. CNN says one woman apparently had a panic attack earlier, but that’s the only injury reported thus far. 2:45 p.m. news conference coming up any minute now.

Update: The all clear has been given, reports Fox. No word yet on what the hell caused all this.

Update: Good lord. Michelle sends word that the “gunshots” were apparently the sounds of construction work.