Armed officers protecting London Mayor Sadiq Khan accidentally left a bag packed with weapons on a street near his home, it has emerged.
Five people have since been temporarily removed from frontline duties while an investigation is carried out.
The holdall reportedly contained a Heckler & Koch submachine gun, a Glock pistol, a Taser and ammunition.
The Metropolitan Police’s Directorate of Professional Standards has confirmed it is reviewing the incident.
In a statement, it said: "A member of the public called police after finding a bag containing Met-issued firearms and a Taser on a street in south London." Within seven minutes of the call to police, officers arrived at the scene and safely recovered the items.
"At this stage it is believed the bag was misplaced by on-duty officers a short time before the member of the public located it."
The incident happened at about 9.40pm on Tuesday.
Jordan Griffiths told The Sun his pregnant partner discovered the bag by the kerb.
"I could not believe my eyes. There was a handgun in the front pocket and a submachine gun in the main part of the bag."
The scaffolder said he alerted police, who arrived quickly to collect the holdall.
"When they arrived they were really shocked ... I was told they had been left there by one of Sadiq Khan's security officers, which made sense as he lives here," he added.
A spokesperson for the mayor said: "This is a very serious incident, which has been referred to the Met's Directorate of Professional Standards.
"The Met must now take all steps to ensure an incident like this never occurs again."
