At least seven people were killed yesterday when part of a ferry dock collapsed on Georgia’s Sapelo Island, where crowds had gathered for a fall celebration by the island’s tiny Gullah-Geechee community of Black slave descendants.

The Georgia Department of Natural Resources, which manages the island and operates its ferry service, said on Sunday that 20 people went into the water when the gangway collapsed and that three people remained in critical condition. All of the people who went into the water have been accounted for.

Melvin Amerson, the McIntosh County coroner, identified the names on Sunday afternoon. All seven were visitors to the island: Carlotta McIntosh, 93, of Jacksonville, Fla.; Charles L. Houston, 77, of Darien, Ga.; Isaiah Thomas, 79, of Jacksonville; Jacqueline Crews Carter, 75, of Jacksonville; Cynthia Gibbs, 74, of Jacksonville; William Johnson Jr., 73, of Atlanta; and Queen Welch, 76, Atlanta.

The middle of the gangway, built in 2021, collapsed because of a structural failure. The cause of that breakdown is still under investigation, said Walter Rabon, the commissioner of the natural resources department.

Hundreds of people visited Sapelo Island on Saturday to attend an annual festival that celebrates the heritage of the Gullah-Geechee people, said Griffin Lotson, the mayor pro-tempore of the nearby city of Darien. Sapelo Island is about 60 miles (97 kilometers) south of Savannah, reachable from the mainland by boat.

The Gullah-Geechee, who live along the coasts of the Carolinas, Georgia and northern Florida, are descendants of enslaved West African people who were brought to the southeastern United States more than two centuries ago. The Gullah-Geechee who live on Sapelo, a small island with only a few dozen permanent residents, are descendants of enslaved people who were brought there early in the 19th century.

The Sapelo Island festival honors their language, cuisine and art, said Mr. Lotson, a seventh-generation Gullah-Geechee.

“The day is about all of the culture,” he said by phone late Saturday. “From Africa, to the way that it was on the plantation, to the 21st century with the young folks and what they do.”

Vice President Kamala Harris said in a statement that federal support had been offered to local officials to assist the community.

“Even in the face of this heartbreak, we will continue to celebrate and honor the history, culture and resilience of the Gullah-Geechee community,” Ms. Harris said.

At least 7 killed, 6 critically injured after ferry dock gangway collapses on Sapelo Island