Two children were killed and two more are in critical condition after a barge struck and sunk their boat, sending them overboard during a sailing camp in Miami on Monday, authorities said. All six people on the sailing boat were pulled from the water by responders,

According to Coast Guard Sector Miami, the sailboat—with five children and an adult counselor on board—sank after being hit by the barge.

Preliminary information indicates a “barge struck a sailing vessel carrying six people” near Habicus Island, Florida officials said.