SAN DIEGO — Investigators tried today to determine why a 25-foot sailboat capsized in calm water and good weather in San Diego Bay, killing two men and injuring eight others who were thrown into the water.

The accident occurred Sunday near a buoy marking the way from a protected inlet to the channel of San Diego Bay, Coast Guard Petty Officer Henry Dunphy said.

A witness said the rescue scene was chaotic.

“I couldn’t see the boat. I just saw them pulling people onto the launch, doing CPR, and a lot of people screaming and yelling,” witness Ty Alicot told the San Diego Union-Tribune. “It’s pretty hard to turn over a sailboat that big.”

Investigators removed the boat from the water and hauled it to the boatyard to examine it, Harbor Police Cpl. Victor Banuelos said.

Video footage appeared to show the boat had a retractable rudder but it was not immediately clear if it was down at the time of the accident, Banuelos said.

There were no indications of a collision or involvement with another boat.