U.S. Coast Guard

The Coast Guard received word at about 12:25 p.m. that a dinghy and a motor vessel had collided.

The impact caused the dinghy to overturn, and the two people on board -- a father and son -- were thrown into the water, Coast Guard officials said.

The father was able to climb on top of the capsized hull, while the son was trapped underneath the dinghy.

The Coast Guard dispatched a 25-foot response boat and a helicopter to the scene. Both men were taken to San Francisco General Hospital, where officials confirmed Trong was pronounced dead, according to KCBS.

The cause of the collision has not been determined.

A third man originally thought to be missing was not on the boating trip, CBS 5 reported.