LONDON (AP) — A London tram driver was suspended Saturday after video was published that appears to show him asleep at the wheel on the same route where another tram derailed this month, killing seven people and injuring more than 50.

The Sun newspaper published the footage, which it says was taken by a passenger in April. It shows the driver — not the same one as in this month’s crash — seeming to nod off at the controls of the vehicle.

London Mayor Sadiq Khan said he was very concerned by the video. Transit authority Transport for London and tram operator First Group said they were urgently investigating.

First Group said the driver had been suspended and “will now be subject to a full investigation.”

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Rail accident investigators say the tram that derailed was traveling at 44 mph (70 kph) in a 12 mph (20 kph) zone when it came off the tracks on a bend on Nov. 9. One theory being investigated is that the driver lost consciousness.

The driver was arrested on suspicion of manslaughter, but was later released on bail.