The Duke of Edinburgh's car accident, which left two people needing hospital treatment, will be "investigated and any appropriate action taken", Norfolk Constabulary has said.
Norfolk Police said they were following standard procedure where a road traffic collision resulted in injuries.
Eyewitness Roy Warne has described how Philip asked if everybody was all right in the aftermath of an accident which saw his car "tumbling" over the road.
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.
Norfolk Police confirmed in a statement that the baby was a nine-month-old boy.
"The driver of the Kia, a 28-year-old woman, suffered cuts to her knee while the passenger, a 45-year-old woman, sustained a broken wrist.
"Both casualties were treated at the Queen Elizabeth Hospital in King's Lynn and were discharged last night.
"Police can also confirm a nine-month-old baby boy was in the Kia at the time of the incident and was uninjured.
"The male driver of the Land Rover was uninjured.
"Both drivers were breath tested and provided negative readings
"As is standard procedure with injury collisions, the incident will be investigated and any appropriate action taken.
"We are aware of the public interest in this case, however, as with any other investigation it would be inappropriate to speculate on the causes of the collision until an investigation is carried out."