The driver of a coach which overturned on the M40 in Oxfordshire injuring 17 people is to be interviewed by police.
Police said they "suspected driver error" after the Oxford Tube vehicle crashed on Saturday at the northbound exit of junction seven, near Thame.
The injured people were taken to the John Radcliffe Hospital with four of those continuing to receive treatment.
The driver has been suspended under "standard procedure" and will be questioned by police next week.
The double-decker coach had been travelling from London to Oxford when it left the road, crashed through a barrier and rolled on its side down an embankment.
No other vehicles were involved in the M40 incident, Thames Valley Police said.
Officers are investigating whether the coach took a different exit off the motorway as the Oxford Tube normally leaves at junction eight.
One person was thrown clear of the Stagecoach-owned vehicle. Another had to be freed from the wreckage.
Some people with minor injuries were treated at the scene. The driver of the coach was among those taken to hospital.
A spokesman for Thames Valley Police said: "The driver has been released from hospital and we will be interviewing him next week.
"Investigations are ongoing but driver error is suspected."
He said the location of the interview and whether it will be under caution had yet to be decided.
A spokesman for Oxford Tube said: "It is standard procedure, following an incident of this nature, for an employee to be suspended pending the outcome of the investigations into the accident."