An Army laboratory in Utah inadvertently distributed live samples of anthrax to facilities in nine states, prompting an ongoing effort to recover them and and another sample sent to a U.S. military base in South Korea, Pentagon officials said Thursday.

The first live sample discovered was shipped from Dugway Proving Ground in Utah to an undisclosed facility in Maryland and reported by workers there May 22. Live samples from that same batch — labeled “AG1” — were sent to laboratories in eight other states, and could have been distributed from there to additional facilities run by the government or private companies, according to a defense official who spoke on condition of anonymity to discuss the incident.

The Pentagon also said that one sample of anthrax was sent to the Joint United States Forces Korea Portal and Integrated Threat Recognition Program at Osan Air Base. It did not clarify whether that same was live.

“The sample was destroyed in accordance with appropriate protocols,” said Army Col. Steve Warren, a Pentagon spokesman, in a statement.

Warren said the Department of Defense is collaborating with the Centers for Disease Control and Prevention (CDC) in an investigation to determine what happened.

“There is no known risk to the general public, and there are no suspected or confirmed cases of anthrax infection in potentially exposed lab workers,” Warren’s statement said. “Out of an abundance of caution, [the Defense Department] has stopped the shipment of this material from its labs pending completion of the investigation.”

The Pentagon confirmed a U.S. military facility mistakenly shipped live anthrax bacteria to laboratories in nine states and a U.S. base in South Korea. (Reuters)

The lab at Dugway was involved in a Defense Department effort to develop a test to identify biological threats in the field, Warren said. A defense official said an anthrax sample is typically irradiated to kill it, and then distributed to facilities that are involved in the program. It is not clear what wrong in that process.

A broad effort to lock down the other samples began less than a day after the Maryland laboratory reported the live sample, and the CDC was called in, a defense official said. The other samples were sent to labs in Texas, Wisconsin, Delaware, New Jersey, Tennessee, New York, California and Virginia, the official added.

Dugway Proving Ground is an isolated area about 85 miles southwest of Salt Lake City, and is known for testing biological and chemical weapon defense systems. It has suffered at least one significant incident previously: A 2011 lockdown prompted by a misplaced vial of nerve agent. The base was re-opened without any illness after the vial was discovered.

Anthrax is considered one of the most common bioweapons that Americans could face in a terrorist attack, according to the CDC. In 2001, powdered anthrax spores were put into letters that were mailed, infecting 22 people, including 12 mail carriers. Five of the 22 people died.