Authorities are investigating the cause of a partial ferry dock collapse on Georgia’s Sapelo Island that turned a day of celebration into tragedy, leaving at least seven dead and six critically injured as crowds gathered for a cultural festival.

A chunk of a ferry dock collapsed on Georgia's Sapelo Island, where members of the Gullah Geechee community had gathered to celebrate fall.

Georgia authorities say they are investigating the “catastrophic failure” of a dock gangway that collapsed, killing seven on Sapelo Island.