A man in his 30s fell from a flyover onto a dual carriageway after a police chase across east London early on Friday.
A pursuit began when the vehicle failed to stop. A police helicopter was brought in to help track it.
Fifteen minutes later, the car stopped in Poplar on the A1261 Aspen Way, near the Cotton Street roundabout.
Four males were arrested on suspicion of theft of a motor vehicle and possession of an offensive weapon. Police fired a Taser at one man who was taken to hospital as a precaution.
Shortly afterwards paramedics and London’s Air Ambulance were called after another man — believed to be aged in his 30s — fell onto the carriageway below. A Metropolitan Police spokesman said: “He was taken to hospital after suffering head and facial injuries, though his condition is not thought to be life-threatening.
“As is protocol, the Met’s directorate of professional standards have been informed. The flyover was closed and diversions in place have since been lifted.”
A witness said: “There were police trying to help him. It looked like he was seriously injured.”
A police cordon remained around the scene this morning as investigators worked to establish the events that led to the man falling from the flyover.
A resident of Elligood Court near the roundabout where he fell said: “I heard sirens and saw loads of blue lights near the roundabout. We just thought it was an accident as it’s a very dangerous stretch of road.”
Another local, Tracey Abrahams, 23, said: “It was bedlam near the roundabout, lots of police and ambulances. To be fair it’s very busy for the police around here.”