A mass brawl at a social club may have been the result of a bikers' feud, police have said.
An armed gang of 13 men descended on the Forman Institute in Blindley Heath, near East Grinstead, on Wednesday.
Six men - believed to be part of a biker group - were injured in the clash in an outbuilding just after 19:30 GMT, Surrey Police said.
Three men remain in a serious but stable condition in hospital. No arrests have been made.
The victims were aged between 20 and 62.
Police said they were keeping "an open mind" as to the reason for the brawl, in which various weapons were used.
Insp Dan Gutierrez, borough commander for Tandridge, confirmed a biker gang feud was one of "a number of theories and hypotheses" being considered.
"But at the moment there is no evidence to suggest that that's the absolute case."
Det Ch Insp Chris Friday, said the investigation was in its early stages and officers were "still trying to piece together what has exactly happened".
"We understand that this is a concerning incident for local residents but we do not believe there to be a wider threat the public and it is extremely rare for an incident of this nature to occur," he added.