The Coast Guard is among responders searching Sunday for a missing passenger on a sailboat that grounded off Hawaii’s Big Island.

The Hawaii County Fire Department also is searching for the missing passenger near Kaupuleu.

The Coast Guard says watchstanders were notified by the fire department of a flare sighting Saturday.

The flares were determined to have been fired by the crew of the 74-foot sailing vessel Hawaii Aloha. The crew abandoned ship into a life raft, and for of the five boaters were rescued from the raft.

The sailboat subsequently went aground. The Coast Guard says one person on board the vessel remains missing, and it’s unknown if that person remains aboard the grounded sailboat.

A search of the vessel is planned for Sunday.