A day after being rescued by the U.S. Coast Guard, a woman who, along with her family, was stranded on a secluded island in Massachusetts after fleeing a burning boat, has passed away. The incident occurred when their vessel caught fire while anchored overnight in a cove.

Cynthia Sullivan, aged 73, succumbed to her injuries on Thursday, as confirmed by a family member’s Facebook post shared the following day. Boston 25 News reported on the unfortunate outcome.

The family’s dog, who alerted Cynthia, her husband Patrick Sullivan, 72, and their 37-year-old son, Tyler, to the blaze as they slept on their 30-foot powerboat, The Third Wave, did not survive the fire.

Upon waking to find their boat engulfed in flames, the Sullivans swam to Naushon Island, a small landmass located about four miles from Martha’s Vineyard.

Injured and scorched, the family sought refuge inside a barn on the island. They remained there for over 24 hours until a marine radio washed ashore on Wednesday morning, which allowed Tyler to call for assistance.

The U.S. Coast Guard conducted a helicopter rescue operation this week, saving the family of three from the isolated island. They had been forced to swim there after their boat was consumed by fire, according to the agency.

“Mayday, mayday, mayday, our ship went down in Tarpaulin Cove,” Tyler is heard saying in a radio transmission to the Coast Guard. “Our ship burned while we were sleeping, and we barely escaped.”

A Coast Guard helicopter rescue crew soon arrived and airlifted the family to Cape Cod Hospital in Hyannis.

A family member had reported the Sullivans missing when they didn’t arrive home Tuesday and calls to their cellphones, which went down with the boat, went straight to voicemail.

Multiple agencies searched the area Tuesday night and early Wednesday, and were unable to get accurate pings from the family’s submerged phones until Tyler reached them on the recovered handheld radio, according to the Coast Guard.

The Coast Guard airlifted the family to Cape Cod Hospital in Hyannis. (USCG)

In a Facebook post, Chris Sullivan memorialized his mother and provided updates on his father and “hero” brother. 

“She went in peace. We played her some John Mellencamp as she passed, he was her absolute favorite, she adored him,” Sullivan wrote. “This hurts more than anything I could have ever imagined, I am leaning on my close friends and family and my two young children. We will get through this together.

“My dad is awake and breathing on his own. My brother saved both of them, he was able to get them off the boat under extremely chaotic circumstances, he doesn’t want to be called a hero, but he is. Again, thank you for all the support, it means the world.” 

The island is about four miles from Martha’s Vineyard.  (John Greim/LightRocket via Getty Images)

“Quick thinking and having quality equipment allowed the family to survive and call for help,” Scott Backholm, a search and rescue mission coordinator from Coast Guard Sector Southeastern New England, said in a statement. “Mariners are encouraged to pursue first aid training and ensure their vessels are outfitted with proper safety equipment.”

The Sullivans had left nearby Falmouth, Massachusetts, last Friday and had planned to return Tuesday afternoon.