A man has been shot at a 50th birthday party in a pub, police have said.
The 29-year-old victim sustained a thigh wound at The Swan in Huyton, Merseyside at about 23:35 BST.
He attended hospital, and was admitted for treatment. His injuries are not life-threatening, police said.
The witness is "refusing to co-operate with detectives" said police, who are looking for an attacker described as a 5ft 7in (1.7m) tall white man in his 20s.
Det Ch Insp Siobhan Gainer said: "The offender involved in this incident needs to be taken off the streets and put before the courts - he was prepared to fire a weapon in a room full of people and didn't care about the consequences."
"We need people from the community who may have any information which could help us to contact us."
The offender was wearing a navy blue bubble jacket with the hood pulled up, black tracksuit bottoms and a balaclava.
Det Ch Insp Gainer said the force had seen a significant decrease in firearm discharges and anti-social behaviour since a group of 22 people was jailed for gun and drugs offences.