A 53-year-old man drowned near Alessandro Island and Lake Perris State Recreation Area on Labor Day, California State Park officials announced.

The man was pronounced dead at a nearby Kaiser Permanente medical center at 1:22 p.m. Monday, Sept. 5. His identity has been withheld until relatives are notified.

State park officers and lifeguards responded to emergency calls near the east side of Alessandro Island at approximately 12:30 p.m., according to John Rowe, an Inland Empire state park superintendent.

Witnesses reported that the victim had been jet skiing and then removed his lifejacket to swim, Rowe said. He began to struggle in the water shortly after.

Once bystanders realized the man was unresponsive, they pulled him up from the water onto their boat.

The man, Rowe said, was unresponsive and not breathing after the rescue.

“Officers and lifeguards performed life-saving measures and drove the victim by patrol vessel to the nearby patrol dock where CalFire and an AMR unit was staged,” Rowe said.

The man was then transported to a nearby hospital, where he was pronounced dead.

Further details on the man’s identity or what caused the drowning were not immediately clear.