Three people were killed on Saturday when a catamaran they were aboard flipped over and ejected them into the Caloosahatchee River on Florida’s Gulf Coast, authorities said.

The tragedy unfolded around 4 p.m. local time near the Cape Coral Yacht Club between Cape Coral and Fort Myers, according to the Lee County Marine Emergency Response Team.

Four people were aboard the catamaran when it overturned, officials said.

During a search by state, local and federal agencies, three of the victims were pulled from the river on Saturday. Two of the victims were pronounced dead, while the third victim remained in critical condition in a hospital on Sunday, officials said.

On Sunday, a fourth victim, described as a 60-year-old missing since the accident, was found dead and retrieved from the river following an extensive search by the U.S. Coast Guard, according to the Florida Fish and Wildlife Conservation Commission.

The names of the three deceased victims were not immediately released.

The cause of the boating accident remains under investigation, according to the Coast Guard.