As people turned to Twitter to get updates on the shots fired at the Capitol, the office of the Senate Sergeant at Arms took advantage of a new Twitter tool that allows certain accounts -- such as government offices -- to send push notifications or text messages directly to the phones of followers who sign up to receive emergency alerts. The service started on Sept. 24.

While several members of Congress, journalists and other eyewitnesses on the Hill turned to Twitter to provide live updates on the event, several official government Twitter accounts, including the official account for the Capitol Visitors Center are not currently being updated, due to the shutdown.