A 15-minute thunderstorm struck in Los Angeles on Sunday as thousands were visiting Venice Beach, killing one man and injuring 13 others, according to a report from ABC News.

The man who was killed has been identified as 20-year-old Nick Fagnano, who was swimming when he was struck. Lifeguards pulled him out of the water and performed CPR before he was taken to the hospital, where he later died.

Eight others were taken to the hospital, including a surfer who reportedly was in critical condition. The Los Angeles Times claimed that the storm struck when around 20,000 people were out at the southern part of Venice Beach.

Such thunderstorms are extremely rare in the Los Angeles area and authorities say that many people didn't know how to react when the storm rolled in. Eyewitnesses say the thunder was so powerful that it shook houses and set off car alarms.

Bill Patzert, a NASA climatologist, said that Sunday's storm happened after an intense high-pressure system pulled a mass of hot, moist air up from Mexico and the Gulf of California, which created unstable weather conditions. Typically, these systems don't make it past the desert and mountains, he said.

"Coastal Southern California is virtually lightning-proof. Because it's so unusual, people are not sensitized to the dangers," Patzert said.

One of the people who was struck by lightning likened it to getting hit over the head with a board, followed by full-body tingling.

"It sounded like a sonic boom," said Stuart Archer, who was at the beach playing volleyball. "It literally shook the buildings. Shook us on the courts."

Archer said it felt like somebody punched him in the head, then his muscles locked up and he fell over.

"I looked up and everybody else was falling over," he said.

According to the National Weather Service, lightning has killed 15 people across the U.S. so far this year, six of whom were in Florida. This is California's first lightning death of the year.