The US Capitol was temporarily shut down on Monday as a precaution after a fire broke out near the complex, underscoring security jitters days before President-elect Joe Biden's inauguration, said the Capitol Police.

"All buildings within the Capitol Complex: External security threat, no entry or exit is permitted, stay away from exterior windows, doors. If outside, seek cover," US Capitol Police said in a message.

The American capital has been put under heightened security with the deployment of nearly 25,000 National Guards to prevent any mishap like the Capitol breach when hundreds of pro-Trump supporters raided the building. The incident resulted in five deaths and many injuries.

In days after that, an unprecedented level of security has been placed in the entire Washington DC. The FBI and other intelligence agencies have received various reports of armed violence in the city.

The entire city has now been converted into a garrison city with thousands of armed national guards being placed in every nook and corners of the city and eight feet high iron barricade around key places including Capitol Hill and the White House.

US Capitol Police said that the message of lockdown was due to an "external security threat located under the bridge on I-295 at First and F Streets SE." The lockdown was lifted later.

Local media reports claimed that there was a fire a few blocks away from Capitol Hill resulting in the security message.

Personnel participating in the rehearsal of the inauguration were evacuated quickly. President-elect Joe Biden is scheduled to be sworn in as the 46th President of the United States on January 20.