If you've been watching the news, you'll know that shots were reported in the garage of the Rayburn House Office Building about 10:30 am. The Capitol was locked down briefly, and Rayburn remains so while a room-by-room search continues. There are no reports of injuries except one young lady who was evacuated after suffering an anxiety attack.
The search of the Rayburn building is a non-trivial affair. What the television coverage isn't telling you is that the whole Capitol complex -- the Capitol itself, the House and Senate office buildings -- are all connected by a network of underground tunnels. Searching them, if it is to be done, would take many hours.
Capitol Police are supposed to have a news con in a couple of minutes. Not much news is to be expected.