Through Twitter, Facebook, emails and cellphones, the Capitol Hill community experienced the first outburst of violence in years through the lens of technology and social media.

Though the chaos lasted only 40 minutes Thursday, the tick-tock might have felt even more protracted for the lawmakers, staffers, reporters and visitors who learned about the frantic series of events in endless streams of information — some of it right, some of it not-so-much.

Twitter reports of the first gunshots began to appear around 2:20 p.m. “Not a joke,” tweeted MSNBC reporter Luke Russert.

“Literally was dragged in by cop as he heard shots fired come over the radio,” tweeted BuzzFeed scribe Kate Nocera.

Sirens were heard approaching the Capitol complex and people looked through windows to see what they could see. Inside the House Daily Press Gallery, the PA system relayed in barely comprehensible instructions cut with static to “shelter in place,” and announcements that the Capitol was on lockdown after guns had been fired on the Senate side. The doors soon were locked.

On the House floor, Democrats were lining up to make unanimous consent requests to bring up a clean continuing resolution when the session was called to recess. Trapped inside the chamber, lawmakers lingered, checking phones or watching the news on their iPads.

House Minority Leader Nancy Pelosi, D-Calif., and her chief of staff were at one point briefed by House Sergeant-at-Arms Paul Irving. Nearby, Rep. James E. Clyburn of South Carolina, the House’s third-ranking Democrat, didn’t seem too worried. Looking down from the gallery, he could be seen joking with Democratic colleagues Emanuel Cleaver II of Missouri and Sanford D. Bishop Jr. of Georgia.

Across the Capitol, the Senate also suspended legislative business. Senate Sergeant-at-Arms Terrance Gainer was briefing Senate Majority Leader Harry Reid. Sen. Jeff Flake, R-Ariz., was trying to get to his office across from the Capitol, but was blocked at the door.

Reports on Twitter and on local news stations suggested different versions of events. A suspect was in custody; a suspect was dead; an officer was injured; an officer was dead.

There was a news conference being set up outside, but no one who was still inside the Capitol could get there. Some office doors were unlocked, but police officers blocked the exits out to the streets.

Few had a clear view of what was going on, maddening the journalists who were desperate to report the news. In the Dirksen Senate Office Building, journalists were instructed to lie down on the floor until the danger passed. Tweets were retweeted and television news anchors broadcast live calls from journalists trapped inside the Capitol who could share only their first-hand accounts.

By the time the “all clear” was issued shortly before 3 p.m., some of the furious social media flurries had petered out, as people put down their mobile devices to emerge from where they had been detained. There was a hush around the Capitol, even with the halls less frantic than usual given the shutdown’s suspension of tours and furloughs of scores of staff.

“The incident requiring staff to shelter in place has concluded,” a Senate-side email message read. “Occupants may exit their shelter in place location and return to normal operations.

“Thank you for your cooperation,” it read.