A terminal at the Port of Charleston in South Carolina was cleared on Thursday evening while officials investigated the threat of a dirty bomb on a container ship.

The US Coast Guard said that a 'YouTube conspiracy theorist' notified them that there was an explosive stowed away on the Maersk Memphis.

The Memphis had just returned from a trip to the Middle East on Wednesday, and the Coast Guard immediately evacuated all workers while federal, state and local officials began their search.

The FBI was even called to the scene, but a thorough sweep of the ship found nothing and at 3:30am on Thursday the Coast Guard said there was no existing threat to the port.

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Sweep: The Coast Guard evacuated two terminals and cleared a safety zone of one nautical square mile after receiving a tip about a 'dirty bomb' (Charleston ship terminal above)

No go: A massive sweep of the ship got underway soon after but no bomb was found (terminal above)

George Webb, the man who informed the Coast Guard of the alleged 'Dirty bomb,' is now being questioned by authorities.

Law enforcement agents scanned four containers aboard the Maersk Memphis ship in the Wando Terminal after reports of a 'potential threat' on Wednesday, the Coast Guard said.

Maersk Line, the world's biggest container shipping company, said the U.S. 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.

The Maersk Memphis, a 300-meter vessel, arrived in South Carolina from New York at about 7:30pm on Wednesday, two months after departing the Middle East.

On its way back to the South Carolina the ship made stops in United Arab Emirates, Pakistan, India, Oman, Egypt and Spain.

Courtesy of Live5News.com

Ship shape: A individual later identified as George Webb called in to say that the device was on the Maerfsk Memphis (above), which had just returned from the Middle East

It was just 30 minutes after the ship had docked that the tip came in from Webb.

In addition to a sweep of the ship, the Coast Guard also closed an area of one nautical square mile to board traffic.

The terminal reopened once again on Thursday morning.