Seven people are believed dead after a gangway that is part of a marina collapsed on Sapelo Island, Georgia, on Saturday.

According to the Georgia Department of Natural Resources, at least 20 people went into the water when the structure gave way before 4:30 p.m., prompting a response from the U.S. Coast Guard and state and local authorities.

The number of people injured and the extent of their injuries are unknown, the agency said.

“Georgia DNR and several other emergency agencies deployed boats with side-scan sonar and helicopters for search and rescue operations,” it said. “The gangway has been secured on Sapelo Island and the incident is currently under investigation.”

In a statement, Georgia Gov. Brian Kemp said he, his wife and daughters are “heartbroken by today's tragedy on Sapelo Island.”

“As state and local first responders continue to work this active scene, we ask all Georgians to join us in praying for those lost, those still in danger, and their families,” he said.

The McIntosh County Sheriff's Office said on Facebook that those concerned about loved ones on the island should contact a reunification center set up at Elm Grove Baptist Church in nearby Meridian.

According to the ministry, the gangway is used by public ferries, the University of Georgia research trawler and some small boats.

The Sepalo Island Cultural and Revitalization Society organized its annual Cultural Day celebration on the island on Saturday, calling it “our most celebrated event.” It is not clear whether the revelers were on the gangway.

Sapelo Island, on the Atlantic coast, is about 72 miles south of Savannah.