Seven people died on Saturday when a gangway collapsed at a ferry dock on a Georgia island, the site of a festival celebrating the heritage of the Gullah Geechee, a community of descendants of formerly enslaved people in the Southeast.

People waiting for the ferry described hearing the crack of a gangway on a ferry dock at Sapelo Island, about 70 miles south of Savannah, Ga., followed by the sound of screams and the horrific sight of floating bodies. The authorities are investigating what caused the gangway to collapse.

Here is what we know so far.

Who are the Gullah Geechee?

The most popular event of the year on Sapelo Island — a day honoring the Gullah Geechee culture — took place on Saturday. Hundreds of visitors from Georgia and around the world visited the island, which is accessible by ferry and has only a few dozen year-round residents.

Some Gullah Geechee, a people who are descended from enslaved West Africans, live on the island, while many others live along the coasts of the Carolinas, Georgia and northern Florida. During the annual festival on Sapelo Island, traditional Gullah Geechee food like smoked mullet is served, and performers present poetry and sing African spirituals.