Foul play is not suspected in the Saturday shooting of a fisherman on Falcon Lake, a waterway straddling the U.S.-Mexico border known for piracy and drug trafficking-related violence, the Zapata County Sheriff in Texas said.

Falcon Lake made national headlines last year as the place where American David Hartley was last seen. His wife claims he was shot in the head while they were riding their Sea-Doo watercraft and his body has not been found.

On Saturday, however, "pure stupidity" was to blame for a fisherman being shot on the lake, not criminal activity, Zapata County Sheriff Sigifredo Gonzalez said.

A fisherman on the U.S. side of the lake heard shots coming from land, Gonzalez said. Under the impression that the shots were the result of someone target practicing, the fisherman decided to get closer, Gonzalez said.

"A guy was target practicing on land. The fisherman was shot in the arm from gunfire coming from the U.S. side. It was just pure stupidity," he said.

The fisherman was airlifted to safety, Gonzalez said. No one has been arrested in the incident.