20 people injured in lightning strike while swimming at South Carolina beach

Twenty people were injured by a reported lightning strike while swimming at a beach in South Carolina, officials said.

The incident occurred at approximately 5 p.m. on Tuesday, when multiple agencies responded to a "reported electrocution" due to lightning at Dominion Beach Park near the Lake Murray Dam in Lexington County, South Carolina, officials said in a press release.

When first responders arrived on the scene, 20 patients -- eight adults and 12 juveniles -- had been injured by the strike, officials said.

Eighteen of those individuals were treated at the scene, while 12 were sent to three local hospitals with non-life-threatening injuries, Vanessa Diaz, the public information officer for Lexington County, told ABC News in a statement.

All of the patients are expected to recover, officials said.

When the strike occurred, it was a "bright and sunny day" at the lake, but then a bolt of lightning hit the water and "energized a metal cable with buoys on it that surrounds the swimming area," the Irmo Fire District said in a statement.

"Lightning can strike far away from a cloud. It doesn't seem logical but a few hundred of us are believers today," the fire district said.

Several people had swam out to the buoys and were holding the cable when the lightning hit, with others nearby in the water, the fire district said.

"Everybody got quite a jolt, we're so fortunate that injuries were not worse than they were," the fire district said.

Dominion Beach Park is expected to reopen on Wednesday "following safety assessments and clearance from authorities," Lexington County officials said.

This week is Lightning Safety Awareness Week, which began in 2001 "in order to call attention to lightning being an underrated killer," according to the National Weather Service. So far this year, there have been four reported deaths from lightning strikes in the U.S., according to the National Lightning Safety Council.