Three British tourists are recovering in a Kenyan hospital after the coach they were travelling in careered off a road and rolled down an embankment.
The coach, which was travelling to Mombasa Airport, was carrying 15 Britons on holiday with First Choice when the accident happened at 7am local time on Saturday.
Witnesses saw the vehicle snake across the road before rolling down the embankment into the path of oncoming traffic on another carriageway.
The Foreign and Commonwealth Office (FCO) said the tourists' injuries are not believed to be life-threatening.
Mark Bizley, who was travelling behind the coach, told BBC Radio Solent that it lost its grip and started to snake across the road.
"I could see the driver was really struggling to keep the vehicle straight. His right-hand wheels went over the edge of the tarmac and, as soon as the wheels left the road, the bus rolled," he said.
"That side of the coach stopped snaking and the forward momentum turned the bus over and it rolled down the embankment into the other carriageway, which was busy."
A spokeswoman for First Choice confirmed that three British tourists were injured, and said it is not yet known what caused the coach to lose control.
An FCO spokesman said: "Our team in Mombasa is providing consular assistance to the British nationals who have been affected.
"We are working very closely with the tour operator. Some British nationals remain in hospital receiving treatment for injuries, accompanied by their families. The remaining passengers will be leaving Kenya."