SAN DIEGO - Authorities sought today to determine who opened fire during a St. Patrick's Day melee at an upscale Polynesian-themed resort in Mission Beach, killing a 28-year-old man.

The brawl, which involved 20 to 30 people, erupted inside a guest room at Bahia Resort Hotel on West Mission Bay Drive about 10:20 last night, then spilled out onto the grounds, according to San Diego police.

A short time later, shots rang out, SDPD homicide Lt. Kevin Rooney said.

The victim, whose name was withheld pending notification of his family, died at the scene.

It was unclear what sparked the fracas, though gang members were believed to be involved, according to broadcast reports.

A number of people fled as officers arrived, police said.

"I guess our appeal today is to those people who chose to (leave the scene). We would appreciate it if they would think twice about it and call us back," Rooney told KGTV.