PORTLAND, Maine (AP) — The Coast Guard said Monday it has launched a formal investigation into a fatal accident aboard a historic schooner off the coast of Maine in which a mast fell and killed one person and injured three others.

The main mast of the schooner Grace Bailey splintered and fell onto the deck on Oct. 9. The collapse killed Dr. Emily Mecklenburg, 40, a physician from Rockland.

Coast Guard officials said the formal inquiry is intended to determine what led to the collapse and identify anything that can help improve maritime safety.

“As a member of a lifesaving service, I am deeply saddened by this tragedy,” said Capt. Amy Florentino, commander of Coast Guard Sector Northern New England. “The Coast Guard is committed to conducting a thorough investigation aimed at identifying causal factors that will prevent an accident like this from reoccurring.”

The owners of the vessel, the Grace Bailey Navigation Company of Rockland, have no comment on the investigation, said Nicole Jacques, a spokesperson for the company. The vessel carries tourists off the Maine coast and was returning from a four-day trip when the mast snapped late in the morning of Oct. 9.

The vessel was built in 1882. It was about a mile (1.6 kilometers) east of Rockland Harbor at the time. The schooner’s full length is 118 feet (36 meters) and it was in compliance with requirements when it underwent an annual inspection in May, Coast Guard officials have said.

The schooner was involved in three previous accidents in recent years when it was under previous ownership, Coast Guard records have shown. The Coast Guard said Monday that it sent a 47-foot (14-meter) motor lifeboat crew to assist after the mast collapse and transferred Mecklenburg to emergency medical workers, after which she was pronounced dead.

There were 33 people on board the Grace Bailey when the mast collapsed. The other three injured people, who suffered head and back injuries, were transported to hospitals afterward.