Four Marines remain hospitalized — one in critical condition — following a fatal MV-22B Osprey accident in Hawaii on Sunday, Corps officials said Monday today.

Twenty-two Marines were aboard the tiltrotor aircraft when it suffered a mishap during a training exercise aboard Marine Corps Training Area Bellows at Marine Corps Base Hawaii. The Osprey made a hard landing, leaving one Marine dead, about 11:40 a.m., said Capt. Brian Block, spokesman for the 15th Marine Expeditionary Unit.

Relatives of the Marine killed in the incident have been notified, he said. Officials will release the fallen Marine’s name following a 24-hour waiting period.

The surviving Marines were taken to area hospitals on the island of Oahu, home to Honolulu, for assessment and treatment, Block said.

Army Col. Steve Warren, a Pentagon spokesman, told reporters Monday a fire broke out aboard the aircraft, which takes off and lands like a helicopter while flying like a plane. Whether the blaze contributed to or was caused by the mishap remains unknown, he said.

Regardless, the fire contributed to the injuries suffered by Marines aboard, Warren told reporters.

Warren said the incident, which remains under investigation, will not immediately change the way the aircraft is utilized used by the U.S. military.

Despite the incident, the 15th MEU will continue sustainment training in Hawaii prior to steaming for the Asia-Pacific and Middle East regions, Block said in a news release. The MEU, comprised of amphibious assault ship Essex, amphibious dock landing ship Rushmore and dock landing ship Anchorage, departed San Diego on May 10 for a seven-month deployment with the Essex Amphibious Ready Group.

At more than 4,500 Marines and sailors strong, the MEU includes Battalion Landing Team, 3rd Battalion, 1st Marines; Marine Medium Tiltrotor Squadron 161 (Reinforced); and Combat Logistics Battalion 15.

Staff writer Andrew Tilghman and USA Today contributed to this report.