Two people died on Monday after a barge struck a sailboat off Miami Beach, throwing children overboard who had to be rescued from the water, the authorities said.

The sailboat was carrying an adult woman and five children near Hibiscus Island in Biscayne Bay when it was hit, according to the Florida Fish and Wildlife Conservation Commission.

The children were participating in a program through the Miami Youth Sailing Foundation, according to the Miami Yacht Club. Divers and rescue boats from several agencies responded and pulled all six people from the water, the commission said.

Two people later died, according to Chief Petty Officer Stephen Lehmann, a spokesman for the Coast Guard, who did not immediately know how old the victims were.

Three children had been taken to the Ryder Trauma Center at Jackson Memorial Hospital in Miami in critical condition, and one had been taken there in stable condition, Lt. Pete Sanchez, a spokesman for the Miami Department of Fire-Rescue, said in an earlier interview.

A fifth child was evaluated on the scene but did not go to the hospital, Lieutenant Sanchez said. The children ranged in age from 8 to 12, he said. The adult woman — a camp counselor — was in stable condition and did not go to the hospital, he said.

Lieutenant Sanchez said the authorities received several calls of a boating accident near Hibiscus Island in Biscayne Bay at 11:16 a.m. Some of the calls reported a submerged vessel with missing occupants, according to Miami-Dade Fire Rescue.

When rescue personnel arrived, they called for additional assistance, Lieutenant Sanchez said. Local television footage showed several rescue boats surrounding a barge.

Because of the swift response from local agencies, “all persons were located and removed from the water,” Miami-Dade Fire Rescue said in a statement.

The Miami Yacht Club said in a statement that it was still gathering facts about what had happened. “Our priority is the safety and well-being of everyone involved, and we are working closely with the appropriate authorities and organizations to understand the situation fully,” it said.