At least seven people were killed after part of a boat dock collapsed, sending at least 20 into the Atlantic waters off the coast of the US State of Georgia.The accident also caused multiple injuries, and US Coast Guard ships were searching through Saturday night for missing people.A gangway that was crowded with people waiting for a ferryboat collapsed late Saturday afternoon on the Sapelo Island in Georgia, about 60 miles south of Savannah, said Tyler Jones, a spokesperson for the Georgia Department of Natural Resources, which runs the ferry.’We and multiple agencies are searching for survivors,’ Jones said.Coast Guard helicopters and boats equipped with sonar immediately began search-and-rescue operations, officials said. The cause of the accident was not immediately clear.Sapelo Island is only reachable by boat and the state-run ferry takes about 20 minutes to reach its shores.