Seven people have been arrested after a police officer was knocked unconscious in an attack by a gang in Preston.
Lancashire police said the officer was assaulted from behind by a group of 10 people while on patrol in Avenham, Preston.
Seven people, aged between 14 and 32, have been arrested on suspicion of wounding and are in police custody.
DCI Ian Dawson of Preston Police, urged anyone with information to come forward and call the 101 number.
He said: "This is a disgraceful incident against a highly respected police officer who was simply doing his job and trying to keep the community safe.
"Our investigation is still ongoing and a number of other people are actively being sought.
"Fortunately, incidents of this nature are rare but they will not be tolerated and we need the public's help to bring those responsible to justice."
The officer was taken unconscious to the Royal Preston Hospital, where he later regained consciousness and was treated for cuts and bruises to his face.
People with information can also contact the independent charity Crimestoppers anonymously on 0800 555 111 or on-line at Crimestoppers-uk.org.