The US Capitol complex was briefly locked down after a fire broke out at a nearby homeless encampment

• The US Capitol went into lockdown Monday following an "external security threat," a message sent to people inside the complex read.
• Staffers in the building were sent an emergency message telling them "no entry or exit" into the building was permitted.
• Some people inside a portion of the Capitol building reported on social media that they had been evacuated.
• The alert was promoted following a fire at a nearby homeless encampment, law enforcement officials said.
• The fire was quickly extinguished, according to DC Fire and EMS, and the Capitol was taken out of lockdown just before 11:30 a.m.

The US Capitol was briefly placed into a lockdown Monday morning following an "external security threat" that turned out to be a fire at a nearby homeless encampment, law enforcement officials said.

The lockdown was lifted just before 11:30 a.m. in Washington, Capitol Police said, according to Fox News' Chad Pergram.

People who were in the West Front of the US Capitol building were evacuated, according to multiple social-media reports. People in the Capitol Complex were warned to stay away from windows and doors, and those outside were told to seek cover, multiple outlets reported.

"In an abundance of caution following an external security threat under the bridge on I-295 at First and F Streets, SE, Acting Chief Pittman ordered a shutdown of the Capitol Complex," US Capitol Police said in a statement. "There are currently no fires on or within the Capitol campus."

DC Fire and EMS said Monday that they extinguished the fire at a homeless encampment. The occupant of the tent where the fire occurred was using propane, according to DC Fire. The occupant suffered non-life-threatening injuries and refused medical attention, DC Fire said.

Members of Congress and their staff were told to shelter in place while authorities investigated the situation, US Capitol Police said. A spokesperson for the Metropolitan Police Department of the District of Columbia confirmed the fire started at a homeless encampment and said people inside the Capitol were alerted due to the proximity to the complex, according to the Washington Post.

Videos of smoke not far from the Capitol complex had circulated across social media Monday morning amid reports of the lockdown.

The alert came as security at the complex has been increased to unprecedented levels ahead of President-elect Joe Biden's inauguration on Wednesday. A group of pro-Trump rioters stormed the Capitol on January 6 while lawmakers were inside, prompting the unprecedented security measures.