A section of the Port of Charleston in South Carolina was shut down for several hours Wednesday night after a tip from a far-right YouTube conspiracy theorist warned that a dirty bomb might be on a container ship moored there, officials said.

A section of the Port of Charleston was closed for about seven hours as nearly a dozen federal, state and local agencies searched and turned up nothing.

The episode began around 8 p.m. on Wednesday when the Coast Guard said it received two phone calls about a potential dirty bomb — a crude explosive rigged to spray radioactive material — aboard the container ship Maersk Memphis, Lt. James B. Zorn, a Coast Guard spokesman, said on Thursday.

Four containers aboard the ship were scanned and the section of the port that had been closed, the Wando terminal, was reopened around 3:30 a.m. on Thursday.

Lieutenant Zorn said the two separate calls appeared to have been prompted by a YouTube posting and that agencies responded out of “an abundance of caution.”

Read the whole story from The New York Times.