GALVESTON — A vacationing couple helped rescue two teenage swimmers caught in choppy waters near the 51st Street jetty, but a 24-year-old Houston man with the teens was caught in the rip current and drowned.

Kasine Mohmmed died at the University of Texas Medical Branch at Galveston after lifeguards’ attempts to revive him were unsuccessful.

Mohmmed was swimming with his cousin and his girlfriend at about 7 a.m. Monday when the three of them were caught in the current on the west side of the jetty, Galveston Beach Island Patrol Chief Peter Davis said.

The teenage boy swam back to shore on his own but then saw his cousin and girlfriend still struggling in the water and swam back in, Jay Sonnenburg said.

Sonnenburg was walking on the jetty with his family when he heard the swimmers struggling, he said.

“I heard a girl’s voice calling for help,” he said. “The current was pushing her into the rocks. She was banging off the rocks.”

Sonnenburg reached down and grabbed the girl from the water, he said.

A beach patrol officer and Joey Alocer, a beach rental employee, went out in the water to try to rescue Mohmmed and his cousin, who got caught in the current again when he swam out to help.

“We didn’t know what to do,” Sonnenburg said. “I wanted to jump in, but you always hear the stories about how it’s the one who went in to save them that doesn’t make it. I knew I couldn’t swim out that far.”

They were able to rescue the teenage boy, but by the time they reached Mohmmed, he was facedown in the water without a pulse, Davis said.

Alocer and the lifeguards brought Mohmmed to shore on a boogie board, where medics performed CPR, Davis said.

When he was unresponsive, he was taken to the medical branch, where he was pronounced dead.

A 911 caller alerted beach patrol about the drowning. Lifeguards don’t start monitoring the beach until about 9:15 a.m., Davis said.

Mohmmed is the sixth person to drown this summer at a Galveston beach, Davis said. Five of the drownings were rip-current related.