A shark attacked four Fourth of July swimmers on Thursday in separate incidents off a south Texas resort island, authorities said.

Capt. Chris Dowdy, a Texas game warden, told the ABC affiliate in Weslaco, Texas, that the shark bit two of the swimmers and injured two more off South Padre Island.

The attacks happened in a span of two hours along the beach and appeared to involve a single shark believe to be about 6 feet long.