A tram driver has been suspended after video emerged appearing to show him asleep at the controls.
The incident happened on Croydon's tram network in south London where seven people were killed in a crash last November.
The London Evening Standard obtained the footage apparently taken by a passenger at around 8am on Wednesday after the packed tram stopped at a set of lights in Croydon and failed to move off.
First Group, which is responsible for operating the trams, said the driver has been suspended pending an inquiry.
Mayor Sadiq Khan said he was "absolutely furious" and has spoken to First Group chief executive Tim O'Toole to make his feelings crystal clear.
First Group insisted its "commitment to the safety of our passengers is unwavering".
Leon Daniels from Transport for London added: