12:55 – 12:58 p.m. - 12:55 p.m.
12:55 p.m.: Capitol Police directs all available units to the front of the Capitol, and officers inside are instructed to lock some doors. (via the Washington Post)
12:58 p.m.: Capitol Police Chief Steven Sund calls House Sergeant at Arms Paul Irving to request an emergency declaration and National Guard assistance. (via U.S. Senate committee staff report)