According to reports, a suspicious package was discovered near Downing Street, prompting police to close Whitehall.
The Whitehall government buildings are being cleared, according to a government official.
Hundreds of individuals were observed congregating at Horse Guards Parade.
A police official at the scene said that a road near the residence and office of Prime Minister Liz Truss is closed owing to reports of a suspicious package, which will be evaluated by expert investigators.
Whitehall, located between the Houses of Parliament and Trafalgar Square, is home to a number of government offices, including the foreign ministry, Cabinet Office, and Ministry of Defence.
MPS Westminster stated in a tweet that police were alerted about a suspicious parcel in #Whitehall at 11:42 a.m. on Tuesday, October 18.
“Officers are present and a cordon has been established as a precaution.
The item will be evaluated by trained police.