One man was fatally shot and several people were stabbed when a fight erupted Saturday at a picnic area on the shore of Lake Berryessa in Northern California, authorities said.

Violence broke out at the Oak Shores day-use area about 5:30 p.m., said Henry Wofford, spokesperson for the Napa County Sheriff’s Office.

“There is no word on what actually sparked this altercation,” Wofford said. “This fight escalated; it got very large.”

When sheriff’s deputies arrived, they found one man with a fatal gunshot wound.

Among those who were stabbed, two were flown by helicopter to hospitals, Wofford said. Other victims were taken by ambulance or driven by others to hospitals, he said.

The recreation area near the Napa Valley is a popular spot where people come to wade and swim in the lake. It became a chaotic crime scene, with deputies questioning witnesses into the night.

“We still have multiple investigators at the lake talking to victims and witnesses,” Wofford said Saturday night. “We have a lot of people that we need to talk to. We also have multiple deputies and detectives at local hospitals gathering information right now.”

He said he did not immediately have information about the conditions of those who were wounded.

Investigators were trying to piece together how the violence started and how many people were involved, Wofford said.

No arrests have been made.

“We’re in that mode of, who did what, who’s the victim, and who’s the suspect? So we’re gathering information to determine that,” Wofford said.

The investigation is being led by Napa County sheriff’s detectives. Because of the size of the incident, Wofford said, the county’s Major Crime Task Force is assisting in the investigation.