A yacht and a sport-fishing boat collided in the Pacific Ocean near the U.S.-Mexico border on Friday night, injuring several people, with one in critical condition.

The U.S. Coast Guard told KFMB-TV that there were 28 people aboard the fishing boat at the time of the incident near the Maritime Boundary Line.

It was not immediately clear why the collision happened.

The coast guard immediately began rescue efforts, sending a helicopter, a 45-foot boat and the Cutter Sea Otter.

One person, who was critically injured during the collision, was flown to a hospital in San Diego, while others were transported to land via sea.

The yacht involved in the accident is called Attessa IV. Dennis Washington, an 84-year-old billionaire reportedly owns the $250 million, 332 feet-long yacht. He’s the 88th richest person in America, according to Forbes 2018 list, with a net worth of nearly $6 billion.

According a real-time maritime traffic website, Attessa IV is currently anchored at North San Diego Bay.