Three men have died after the car they were in left the road and careered into trees before rolling down an embankment, police said.
The men, aged 57, 39 and 31, were in a blue Mercedes E Class estate when the single-vehicle crash happened at about 9.50pm yesterday on the A4074 at Sandford-on-Thames near Oxford.
Two other passengers, both women, aged 37 and 29, were taken to the John Radcliffe Hospital in Oxford where they are in a stable condition, Thames Valley Police said.
A police spokesman said: "Police and emergency services were called to the A4074 at Sandford-on-Thames near Oxford at about 9.50pm last night after a blue Mercedes E Class estate travelling towards Wallingford left the road, crossed a verge on the nearside and struck two trees before rolling down an embankment.
"As a result of the collision three men, aged 57, 39 and 31, were pronounced dead at the scene.
"Two other passengers in the car, a 37-year-old woman and a 29-year-old woman, were both taken to the John Radcliffe Hospital in Oxford where they are in a stable condition."
Thames Valley Police appealed for witnesses to call Pc Martin Mann at the joint roads policing unit based at Abingdon on 101, or Crimestoppers on 0800 555 111.
Two of the men who died, aged 57 and 39, are believed to be US citizens.
Pc Mann said: "We are trying to ensure all the victims' next of kin are notified in the proper way and this can take some time.
"Two of the men who died, the 57 and 39-year-olds, are believed to be US citizens and as such we have contacted the US embassy and are working closely with them.
"I would appeal for anyone who witnessed the collision or who saw a blue Mercedes E Class estate in the area around the time of the incident to contact us with information."