Four residents were evacuated from a block of flats in Banbury on Tuesday by firefighters due to a smell of an unknown chemical.
Four fire engines from Banbury, Deddington and Oxford along with Thames Valley Police and South Central Ambulance Service attended Green Hill Court, Lodge Close at about 9pm.
Specialist detection equipment was used by crews wearing breathing apparatus to identify the chemicals involved. The residents received treatment at the scene and were taken to hospital.
Station Manager Simon Sumners said: “Extra care should always be taken when using solvent based materials in confined spaces, all areas should be well ventilated and the manufactures guidelines should be followed”