WASHINGTON — The police were badly outnumbered.

Only a few dozen guarded the West front of the Capitol when they were rushed by thousands of rioters bent on breaking into the building. Armed with metal pipes, pepper spray and other weapons, the mob pushed past the thin police line. One rioter hurled a fire extinguisher at an officer, according to video widely circulated on YouTube.

"They're getting into the Capitol tonight! They're getting in," the man filming shouts in delight.

They breached the line moments later, and rioters soon broke into the building, taking over the House and Senate cha...