Lightning struck a diver's oxygen tank as he surfaced off Florida's Atlantic coast, killing him, authorities said.

The 36-year-old man was diving with three others Sunday off a boat near Deerfield Beach, about 40 miles north of Miami. He had surfaced about 30 feet from the boat when lightning struck his tank, said Deerfield Beach Fire Chief Gary Fernaays.

The other divers struggled to get the man back into the boat and radioed for help, Fernaays said. The victim, whose name was not immediately released, was rushed to the beach, where a rescue crew gave him CPR. He was later pronounced dead at North Broward Medical Center in Pompano Beach.

A severe thunderstorm warning had been in effect Sunday for Broward County.

The Broward County Medical Examiner's Office planned an autopsy to determine if the man died by electrocution or drowned.