Merseyside Police said a 25-year-old man from Stockbridge Village, who was arrested on suspicion of Section 18 wounding with intent, remains on conditional bail.
Det Ch Insp Cath Cummings said: “First and foremost, our thoughts are with the man’s family and friends at this tragic time.
“I know people living in the local community will be understandably upset and concerned, but I want them to be reassured that we are thoroughly investigating the circumstances surrounding this incident.
“A murder investigation is now underway and we are appealing for information. We know there were people inside The Village Chippy at the time, so if you haven’t already done so, please come forward if you have information.”