One person was killed after he attacked a man living on a yacht docked at the Pier 32 Marina in National City Tuesday, police said.

A witness who lives on his yacht in the marina told NBC 7 he was awakened to gunshots and his neighbor's screams at about 4 a.m.

According to the witness, the neighbor was shouting, "Help me, help me. I shot an intruder" after four gunshots rang out.

National City Police Department officers had guns drawn as they arrived at the scene to investigate the reports of gunfire. Officers could be seen aboard the docked yacht, named SeaWeed, for hours.

A couple living on the $2 million yacht was onboard at the time of the shooting, NCPD said.

The man released the mooring lines and set the yacht adrift while he tried to start the vessel's engine, police said.

"You have to know the boat very, very well to do something like that," a witness said. "There was no way for him to be successful at what he was doing. A boat that size, to actually get it away from the marine and do whatever he was going to do."

Investigators said the man forced his way inside the yacht and attacked a male occupant.

During the fight, the suspect was shot and killed.

The occupant went to the hospital with injuries suffered during a fight with the suspect, police said.

The yacht was owned by a driver killed in a fiery Lamborghini crash in downtown San Diego last year, the yacht's captain confirmed to NBC 7. The couple living on board were the parents of the owner.

Michael Llamas, who was also a controversial medical marijuana businessman, was killed when his 2016 sports car struck a curb, a palm tree, and an ornamental anchor, before bursting into flames on Nov. 5, 2017.

Several boaters were evacuated as NCPD conducted their investigation. They were allowed to return to their boats just before 7:30 a.m.

Pier 32 Marina is adjacent to the Sweetwater Channel, which funnels into San Diego Bay.