State health officials are investigating the contents of a case marked with radioactive warnings that was found in a Goose Creek storage unit.

The U.S. Secret Service was serving a search warrant on a locker at Extra Space Storage at 427 Saint James Avenue on Monday night, according to John Kenney, the Charleston office’s Resident Agent in Charge.

“It was a routine investigation,” he said.

At the bottom of the storage unit agents found a yellow, pelican style case with marking on it that said it may contain radioactive material, according to Kenney.

“It was about the size of a cooler,” he said.

The item was reported around 6 p.m., according to an employee who lives nearby. She said authorities told her it was safe to return home about 10 p.m.

Secret Service agents notified the State Law Enforcement Division, who also notified the Department of Health and Environmental Control. Goose Creek firefighters were also called out to the scene.

DHEC has taken responsibility of the case, Kenney said, and the investigation continues. Kenney couldn’t comment on the contents of the case.

DHEC’s Bureau of Radiological Health responded to the scene and secured the material for law enforcement investigation. Law enforcement agencies did take possession of the material, according to DHEC spokesman Mark Plowden.

“Due to the fact that this is a law enforcement investigation, we are unable to comment further,” he said.

Employees at the storage company fielded all questions to their corporate office. No one there could be reached for comment.

Reach Natalie Caula at 937-5594 or Twitter.com/ncaula.