One witness said the woman was being attacked by the man and the confrontation moved into the road, where they were both hit by a car.

It happened in Chippenham Road in Maida Vale, west London, at about 9am.

Firefighters managed to free the man from underneath the car, but despite the efforts of paramedics both people were declared dead at the scene.

Witness Mulugeta Asseratte told PA news agency: "It is a very terrible incident. I was coming up from the bakery to Chippenham Road and suddenly heard shouts of 'stop it, stop it' and it was a girl being attacked by a gentleman.

"In any case, I'm a father of four daughters, such things do happen, and I tried to look and even say 'stop it' and it would not.

"All of a sudden it moved to the street and no sooner than they reached the street than a driver came and hit both of them.

"We were all shocked and shouting and my heart goes out to the families of this fatal incident.

"This is something one sees in movies, not in real life."

Detective Chief Inspector Neil Smithson warned against speculation and said officers were still on the scene.

He said there is not believed to be any further threat to the community and that police were in the process of contacting the victims' families.

Anyone who saw what happened or has relevant information is asked to contact police on 101 quoting the reference 1496/24jan, or to stay anonymous contact Crimestoppers on 0800 555111 or online.