Two dozen vials of E. coli were left in the refrigerator of two Arkansas college students when they vacated their apartment are now being tested by state health officials, though the bacteria isn't thought to pose a health threat.

The bizarre discovery Friday set off a storm of panic, as state and federal agencies sent HazMat teams to the apartment complex in Jonesboro, Ark. Two of the vials were unsealed, and the samples are to be tested Monday at a state Health Department lab as a precaution, county officials said.

One of the tenants was located by authorities and said that his roommate, who returned a week ago to his native home of South Africa had the vials to treat an ailment, officials said.

“We spoke to his roommate, who told us that he used it to treat an illness and that it was a common treatment in his country,” David Moore, director of the Craighead County Office of Emergency Management told FoxNews.com. “We looked into it and we were satisfied with the fact that it was used for medical reasons."

Certain strains of E. coli are used to treat a number of gastrointestinal ailments, including irritable bowel disorder.

A maintenance worker who was cleaning out the apartment found the vials, marked “E-Coli,” inside a foam container after opening the refrigerator, officials said. He notified the building manager, who called the Arkansas Department of Health and the Centers for Disease Control and Prevention. Local authorities, along with the National Guard, immediately shut down the area and spent a majority of the day securing the medical-grade vials for removal.

The apartment complex was not evacuated at the time, and tenants were told there was no danger posed from the discovery. Representatives from the Willow Creek Apartment Complex, where the bacterium was found, did not immediately return calls for comment.

Perry Chiaramonte is a reporter for FoxNews.com. Follow him on Twitter at @perrych