The U.S. Coast Guard on Sunday suspended its search for four people — three British citizens and one American — last heard from aboard a sailing boat that was reported to be in distress 230 miles south of Halifax, Nova Scotia.

Rescuers spent three days searching for the "Free Spirit," a 41-foot vessel that left Newport, Rhode Island, bound for Europe. The boat's operator made an emergency call Thursday morning, reporting seas of 30 feet.

Aboard the boat were Jacek Beilecki, 56, his 19-year-old son, Jacek Beilecki Jr., a family friend, 34-year-old Richard White, and the son's girlfriend, Molly Finn, 21, the Coast Guard said. The father and son are United Kingdom citizens while Finn is American. They live in Newport, the Coast Guard said. White also is a U.K. citizen, but it was not immediately known where he lives.

"Suspending a search is one of the hardest decisions a district commander has to make," Rear Admiral David Pekoske said in a statement Sunday.

Rescuers searched more than 15,000 square miles since Jacek Beilecki's stepdaughter reported his distress call Thursday morning. The vessel was 230 miles south of Halifax and more than 300 miles east of Chatham, on Cape Cod. Beilecki called his stepdaughter via satellite phone.

There has been no further communication with the vessel's crew.

"I understand how difficult it is for family and friends to move forward when a search is suspended without the hoped-for outcome," Pekoske said. "I can assure you that the Coast Guard worked around the clock trying to locate the Free Spirit or its crew."

The search was suspended at 1:45 p.m. Sunday.