Seven people suffered multiple stab wounds when two gangs clashed in what police believe may have been a racially motivated brawl.
About 12 men were involved in the fight outside the Chicago Rock Cafe on Bristol's waterfront on Saturday.
Seven people were taken to the Bristol Royal Infirmary for treatment. Three are still in hospital, and are said to be in a serious condition.
One man has been arrested in connection with the incident.
Det Ch Insp Geoff Spicer said: "The victims are Turkish and there is an indication the antagonists may have been Iraqi Kurds.
"It is primarily the Turkish people who ended up in hospital. The man arrested is an Iraqi Kurd.
"It is possible there is a racial element between those two groups of men as opposed to a wider racial motive."
One knife was recovered from the waterfront and police divers searched the nearby dock area on Sunday for another knife, but officers say they do not know how many weapons were involved.
Translators were brought in from London to assist in the interviews with the injured Turkish men.
Anyone with information is asked to contact police.