Saturday afternoon shoppers in Preston are being asked if they saw an attack on a man in the city.
Preston Police were called to reports of a man being attacked by three men in Church Street.
A 19-year-old man had been walking when he was chased by three males around 5pm on Saturday (1 September).
The group are said by police to have attacked the victim with weapons, knocking him to the floor before kicking and punching him.
The man suffered a serious head injury and was taken to Royal Preston Hospital for treatment.
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One of the group, a 17-year-old boy, was detailed by a member of the public and later arrested by police on suspicion of wounding.
Two other men remain on the run and police are appealing for witnesses.
Detective Constable Richard Shires of Preston CID said: “We believe a number of shoppers were in the area at the time of the alleged offence and can provide us with information.
“If you saw what happened and have yet to speak to police, please contact us.
“We are particularly keen to speak to anyone who saw two men making off from the scene. Any information will be treated in the strictest confidence.”
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Anyone with information should call police on 101 quoting crime reference SA1818521.
Or Crimestoppers can be contacted anonymously on 0800 555 111 or online at crimestoppers-uk.org.