Maersk Line, the world's biggest container shipping company, said in a statement on Thursday the US Coast Guard had informed it of a threat of a "dirty bomb" aboard one of its vessels. It said all crew members were safe and ashore.
Coast Guard officials described the threat as a possible dirty bomb on the Maersk Memphis ship docked in the Wando Terminal, where hazardous materials crews and rescue workers were seen working, an NBC affiliate in South Carolina reported.
The Coast Guard said the threat was "active and ongoing," in a Tweet at 2 am.
The US Coast Guard said authorities were made aware of the potential threat in a container aboard the vessel at about 8 p.m. on Wednesday (midnight GMT) and the terminal had been evacuated.
The Maersk Memphis, a 300-meter vessel, was in New York before arriving in South Carolina at about 7:30 pm, according to Reuters data.
Update: The US Coast Guard Southeast said on Twitter that "Unified Command determines no existing threat to the port. Terminal will reopen and safety zone has been lifted."
There were four containers where a threat was posed at the terminal, it said. "These have been scanned and cleared by authorities."