A stuntman has suffered serious head injuries in a fall while filming Fast & Furious 9 at Warner Bros Studios.
Police and paramedics were reportedly called to Leavesden just before midday yesterday by other members of crew and a man was taken to hospital by air ambulance.
Universal said filming had been halted for the day to deal with the injury.
The man was taken to the Royal London Hospital by helicopter, emergency services said.
A spokeswoman for Universal said: "We had an injury on the set of Fast 9 in Leavesden with one of our stuntmen.
"We have halted production for the day to focus on this situation."
The site has been used to shoot films in the Harry Potter and James Bond franchises.