FORT MYERS, Fla. (CBS12) — One person was killed, and three others were injured after a lightning strike while they were swimming in the Gulf of Mexico at Fort Myers Beach on Friday, according to the Fort Myers Fire Department.

Fire officials said the group was in the water when lightning struck. When first responders arrived, they found one man unresponsive as a bystander performed CPR.

Despite life-saving efforts by bystanders and emergency crews, the man succumbed to his injuries.

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A beachgoer who witnessed the rescue said multiple people immediately stepped in to help before paramedics arrived.

“I went running up the beach. He was lying near the water. There was already a paramedic doing CPR. There was already a nurse doing CPR. They had the AED connected, but he did not have a shockable rhythm, so you just keep doing CPR. We kept making sure that his head was turned to the side, and we just kept doing CPR until paramedics came,” the witness told WINK.

Three other people injured in the lightning strike were taken to a hospital. Officials have not released their conditions.