A man sustained a head injury in an assault in Cleethorpes Market Place.
Humberside Police threw a cordon around the scene outside William Hill bookmakers and a pizza takeaway following the attack at around 10pm last night.
A police spokesman said: "We are investigating a serious incident which has occured in the Market Place in Cleethorpes. We are making a number of enquiries."
A door supervisor, who did not wish to be named, told how he gave first aid to the injured man after raising the alarm and calling 999.
The witness said: "He was in a bad way."
He said the man was with a group of four other men when the attack took place.
Scene of crime officers gathered evidence outside the bookmakers as other officers visited nightclubs and other premises in the area as part of the investigation.
Humberside Police threw a cordon around the scene outside William Hill bookmakers and a pizza takeaway following the attack at around 10pm last night.
A police spokesman said: "We are investigating a serious incident which has occured in the Market Place in Cleethorpes. We are making a number of enquiries."
A door supervisor, who did not wish to be named, told how he gave first aid to the injured man after raising the alarm and calling 999.
Paramedics from East Midlands Ambulance Service treated the man and later took him to Diana, Princess of Wales Hospital, Grimsby.
The witness said: "He was in a bad way."
He said the man was with a group of four other men when the attack took place.
Scene of crime officers gathered evidence outside the bookmakers as other officers visited nightclubs and other premises in the area as part of the investigation.
