We're all over the story of the possible shooting at the Rayburn House Office Building. Our prior coverage is available here and here. There will be another police briefing shortly, which we'll be watching.
For now, a choice quote, from Fox News's TV coverage of developments. Office staffers in Rayburn are being ordered to stay in their offices -- they can't even leave to use the bathroom. When one staffer tried to slip into the hallway, a SWAT team member yelled:
Get back in your office! I don't care if you have to use a waste basket. Get back in your office!
More to come -- another briefing within the hour.