JACKSONVILLE, Fla. -

A 76-year-old man drove his minivan into the St. Johns River early Friday morning and died, according to the Jacksonville Sheriff's Office.

Police received a call from witnesses that a minivan was heading down the St. Johns River Marina Boat Ramp downtown on the Southbank and alerted an off-duty JSO officer.

"The off-duty officer (Mark Muchowicz) dove in to the river and was able to rescue the occupant of the vehicle. However, the occupant was unconscious. He was able to hand over the victim to some officers on shore who immediately performed CPR until rescue arrived," said Lt. R. A. Norse.

The man, identified as Thomas Wester, was transported to Baptist Medical Center, where he died.

"Over an abundance of caution, we called the dive team to search the water to make sure there was no additional occupants," said Norse.

No additional bodies were found. Police believe Wester was the only person in the minivan when it was fully submerged into the river.

"It's a a boat ramp and there's three pylons that are on the walkway, and it was between them. I believe it was probably 25 to 35 feet into the water," Norse said.

Police said there is no indication that alcohol was involved.