According to Daily Mail Online, stuntman Joe Watts was hospitalised after suffering a serious head injury in a 30ft fall at the Warner Bros Studios in Leavesden, Hertfordshire on Monday afternoon. The British stuntman has worked on movies and TV shows including "Game of Thrones", "Kingsman: The Golden Circle", and "Spider-Man: Far From Home".
Diesel reportedly witnessed Watts fall on his head as he performed a stunt in the movie star's place.
"The stuntman fell at least 30ft - maybe a bit more," a source told British newspaper The Sun. "Vin Diesel was seen on set seconds after. He looked ashen, totally in shock and blinking back tears. He saw what happened."
Filming was halted immediately and cast and crew sent home "fearing the worst" the source added. Warner Bros Studios confirmed a man had been airlifted to Royal London Hospital on Monday.
The fall reportedly occurred just before noon on set, and Hertfordshire Police added in a statement: "Police were called shortly before noon today following an incident at Warner Bros Studios in Leavesden, Hertfordshire."
"It was reported that a man had been injured while working at the location and sustained serious injuries. The air ambulance attended and police officers are currently on scene to assist and carry out initial enquiries."
Diesel has had several brushes with tragedy in the past. His stunt double Harry O'Connor was killed filming a para-sailing scene for 2002 action flick "xXx" in Prague while performing a paragliding stunt in the actor's place. And his "Fast and Furious" co-star Paul Walker died aged 40 in a car crash off-set during filming of the franchise's seventh film in 2013.