MINNEAPOLIS (WCCO) — Police in Hawaii say Minnesota resident Thomas Bossert drowned to death Monday morning on the island of Kaua’i.

Investigators say Bossert, 64, was snorkeling in the ocean at about 11:30 a.m. near the Marriott’s Waiohai Beach Club when he got separated from his family.

A nearby resident who was swimming in the same area came across Bossert, who was unresponsive. Lifeguards were alerted, and soon arrived to attempt live-saving efforts. Firefighters and EMS medics also tried to save Bossert, but he was eventually pronounced dead at an area hospital.

Police say lifeguards warned swimmers that morning of dangerous conditions in the ocean.

The local medical examiner’s office is working to determine Bossert’s exact cause of death.