SALEM, S.C. — A man was fatally shot on a lake in South Carolina by a boater who helped rescue him from the water, authorities said.  Nathan Drew Morgan, 29, and a woman were in distress in Lake Keowee last week.  They were not wearing life jackets and their Jet Ski was doing circles in the water without a driver, according to a news release from the Oconee County, (SC) Sheriff’s Office.

Another man and woman on a pontoon boat noticed they needed help and drove over to the pair to help get them out of the lake. The couple on the boat then told authorities Morgan became agitated once he got on board and started assaulting them.

Investigators were told he may have wanted to get back on the Jet Ski. They also believe there may have been an argument between Morgan and the woman he was with before they were ejected into the water.  The woman who was with Morgan pushed him back into the lake in an attempt to diffuse the situation, the sheriff’s office said. The couple on the pontoon helped him aboard again, and the man shot him after a second encounter in fear for his and his wife’s lives.

Morgan died on the boat from a gunshot wound to the chest, the Oconee County, (SC) Coroner’s Office told news outlets.

The sheriff’s office did not release the names of the woman who was with him or the man and woman on the boat, citing the ongoing investigation. Tenth Judicial Circuit Solicitor David Wagner said the shooting of Morgan by an unnamed 74-year-old man was self-defense.