Five people have suffered breathing difficulties after a chemical spill at an Oxford University research laboratory.
Ambulance crews were called to the Chemical Research Laboratory on Mansfield Road in Oxford at 10:08 BST.
A Hazardous Area Response Team and the Thames Valley Air Ambulance emergency response vehicle had been at the scene.
South Central Ambulance Service said the five patients also had runny eyes from exposure to the unknown chemical.
All five people have been taken to the John Radcliffe hospital in Oxford for further assessment.
Oxford University has been contacted but has not confirmed what the substance was.