Two motorists died and third is fighting for his life after a BMW and a Peugeot were in collision on the A371 Axbridge bypass at 3am yesterday.
Both victims are understood to be male. A third man who was travelling in the BMW was taken to Bristol Royal Infirmary with life-threatening injuries.
He was later transferred to Frenchay Hospital, Bristol, where he was in a critical condition last night.
Police have appealed for witnesses and would particularly like to hear from anyone who was on the A371 shortly before or at the time of the collision.
Anyone with information should call Avon and Somerset Police's collision investigation unit on 101.