Investigations are continuing today after a police officer was knocked unconscious in the street.
He was attacked when he was trying to detain a man he had chased down a road in Gloucester on Wednesday.
The man punched the officer in the face several times and threw his bike at him, knocking him unconscious. He was taken to Gloucestershire Royal Hospital with concussion and discharged early yesterday morning.
Inspector Wendy Burford said: "This violent and unprovoked assault reinforces the risk our officers face on a daily basis. We know there were people in the area at the time who may have seen the person responsible or the assault itself and we would urge those people to come forward."
The offender is described as white, 5ft 8in tall, aged in his early 20s and with short brown hair. He was wearing grey jogging bottoms with a blue stripe and a black top. The incident happened in the Podsmead area of the city.
Gloucester city councillor Jennie Dallimore said she was shocked by the attack.
"I am absolutely outraged that this happened," she said. "It is disappointing that there is a minority who spoil it for everyone else. I hope the officer isn't that badly injured, and I really hope the police catch whoever was responsible."
Anyone with information is asked to call police on 101, quoting incident 709 of November 21. Alternatively, information can also be given anonymously on 0800 555 111, or via www.crimestoppers-uk.org. In some cases Crimestoppers offer rewards of up to £1,000 where information leads to a conviction.