A fire at a nearby homeless encampment prompted the lockdown.

On Monday, January 18, just days before President-elect Joe Biden's inauguration, the U.S. Capitol building was placed under lockdown. A small fire at a nearby homeless encampment caused the building to enter lockdown.

The fire has since been put out. No injuries were reported.

"All buildings within the Capitol Complex: The USCP has cleared the external security threat incident located under the bridge on I-295 at First and F Streets SE. All checkpoints have reopened. Return to normal operations," the announcement from U.S. Capitol Police says.

A rehearsal for Inauguration Day was taking place when the temporary lockdown was enforced. A plume of smoke from the fire could be seen and raised security concerns.

*This story will be updated as more information is made known.