U.S. Capitol Police
U.S. Capitol PoliceiStock

The US Capitol building was evacuated Monday amid warnings of an "external security threat" two days before the inauguration of US President-elect Joe Biden.

Smoke was seen rising from the area behind the building.

The evacuation occurred as participants were rehearsing the presidential inauguration in the West Front, the Associated Press reported.

The fire reportedly originated in a nearby homeless encampment.