The Duke of Edinburgh asked if everybody was all right in the aftermath of an accident which saw his car "tumbling" over the road, an eyewitness has said.
Motorist Roy Warne has described how the crash unfolded in front of him as he was driving home on Thursday afternoon.
He immediately went to the aid of passengers, not realising one of the drivers was Philip.
The duke, 97, was driving a Land Rover Freelander, which flipped over after it was hit by another car when he pulled out of a driveway near the Queen's Sandringham Estate in Norfolk, on to a busy A-road.
The woman driving the other vehicle, a Kia, and her female passenger, needed hospital treatment, and there was also a baby in the car.
Mr Warne said he helped the duke get out of his wrecked Freelander through either the sunroof or windscreen after it had rolled all the way over before coming to rest on its side.
The motorist told BBC Radio 4's Today programme: "I was driving home and I saw a car, a black Range Rover, come out from a side road and it rolled and ended up on the other side of the road and there was a huge collision with another car.
"I went to the other car. There was a baby in the back and, with another man, we got the baby out.
"Then I went to the black car to help and realised it was the Duke of Edinburgh."
Asked if Philip was trapped, Mr Warne said: "Yes, he was. I asked him to move his left leg and that freed his right leg and then I helped him get out."
When questioned about what the duke said, he replied: "I can't remember, but it was nothing rude.
"He was obviously shaken, and then he went and asked if everyone else was all right."
Mr Warne said the duke was able to stand and walk immediately after getting out of the car, but he appeared to suggest the duke may have been cut, possibly by broken glass.
"There was a little bit of blood and one of the royal entourage gave me a wipe to wipe my hands," he said.
Buckingham Palace has said that after the accident the duke "saw a doctor as a precaution and the doctor confirmed he was not injured".
Commenting on the circumstances of the crash, Mr Warne added: "I think there's no doubt that it was hit (by the duke's car). That's my recollection.
"I didn't see it come from the side road, I saw it careering and tumbling
across the road and ending up on the other side.
"It would take a massive force and it had rolled on the other side as well."
Asked if he meant that the Freelander had "rolled right over", Mr Warne said: "Yes."