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.

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

Officials were on location in Georgia Sunday investigating the collapse of a ferry dock gangway that left seven people dead and six others critically injured Saturday.

There were life jackets bobbing in the water, people forming a human chain to pass survivors to safety and dead bodies being carried asnore in blankets

Georgia Department of Natural Resources Commissioner Walter Rabon said Sunday morning that at least 40 people were on the gangway and that half fell into the water. The dock gave way before 4 p.m. in a "catastrophic failure," prompting a response from the Coast Guard and state and local agencies.

Investigators have begun looking for reasons behind the failure at a ferry dock on Sapelo Island, the site of a festival celebrating the heritage of descendants of enslaved people.

The gangway collapsed Saturday as festival goes prepared to board a ferry amid Sapelo Island's annual Cultural Day, officials say.

A crowd had gathered for a celebration of the Gullah Geechee people, who have inhabited Sapelo Island since enslaved people were forcibly brought from Africa to the U.S.