A police officer suffered several facial injuries while trying to detain a suspect in Staple Hill last night.
He is said to be in a stable condition in hospital today where he was due to undergo surgery.
Two men have been arrested on suspicion of drug offences.
In a statement Avon & Somerset police said: “At about 7pm yesterday (August 20), a suspicious vehicle was seen by officers outside a building supplies company in Staple Hill. The car drove off and was spotted by officers a short time later in Kensington Road.
“When officers approached the vehicle, the three occupants got out and ran off in different directions.
“One of the suspects was seen heading along a footpath off Acacia Road and an officer chased after him. While detaining the suspect the officer suffered some severe facial injuries. He was taken to hospital where he will undergo surgery. He is in a stable condition.
“Two arrests have been made. A 20-year-old man has been arrested on suspicion of possession with intent to supply a class A drug and a 37-year-old man has been arrested on suspicion of being concerned in the supply of controlled drugs.
“A quantity of suspected class A drugs and other items including cash and mobile phones have been recovered from the scene and the car has been seized for a full forensic examination.”
Further searches were taking place today.