The National Transportation Safety Board has released its preliminary findings after a plane crashed in Bristol, killing a father and injuring his son.

The NTSB says the small plane lost engine power before crashing into the Pemaquid River in August.

NTSB says the pilot, 54-year-old John Hall of New Hampshire, tried to head toward Rockland but hit a sign, a wooden structure and trees.

The plane then crashed into rocks on the shoreline before coming to rest upside down in about four feet of water.

Hall was killed in the crash, while his son, 21-year-old Tyler Hall, was able to get out of the wreck with minor injuries.

The agency says a malfunction caused the engine to fail.

A full report on the crash is expected to take several more months.