A diver drowned after a failed attempt at "buddy-breathing" while exploring an underwater cave at Blue Spring State Park in Orange City.

Rescuers rushed to Blue Spring State Park on Wednesday afternoon after a diving accident was reported there.

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Volusia County Sheriff's officials say 36-year-old Samuel Slack, of Edgewater, experienced equipment problems while diving 80 feet below the surface on Wednesday.

Diving partner 37-year-old Daniel Vansickle says Slack made a "throat slash" gesture, signaling he was having difficulty breathing.

A sheriff's report says Vansickle passed his air regulator to Slack, who wouldn't release it back to Vansickle after about 30 seconds. Vansickle pulled the regulator away, swam to the surface, and yelled for someone to call 911. He dove again and found Slack on his back.

Vansickle carried Slack to the surface and tried unsuccessfully to revive him. He was pronounced dead at Florida Hospital Orlando.

"We have to check their equipment, their regulators, their oxygen tank and everything else to find out what it might have been. We have no idea at this point," Sgt. Bob Rohm said.

Sheriff's divers returned to the park to recover any additional equipment to use as evidence.

The park is a popular scuba diving spot for divers who enter a boil, the entrance to the spring below, to explore the limestone caverns.