A firearms officer is under investigation after losing a Taser when he drove off with it still on the roof of a police vehicle.
The officer put the stun gun on the top of the vehicle as he was leaving a briefing at a firearms base in Norfolk Row in Lambeth, south London, between 7am and 8.30am on Tuesday.
He drove off from the briefing with the Taser and four cartridges still on the roof.
Police realised it was missing at 10am and believed it may have fallen off in the Norfolk Row area before reaching Vauxhall Cross, where the officer stopped for fuel.
The officer, a member of the Metropolitan Police CO19 Firearms Unit, has been taken off operational firearms duties.
Scotland Yard said the Directorate of Professional Standards had been informed and an internal investigation was under way.
Members of the public were warned not to handle the Taser, which is shaped like a handgun but is made of bright yellow plastic.