WASHINGTON (AP) — The Pentagon says it inadvertently shipped live anthrax spores to as many as nine laboratories and is investigating how that happened.

The labs were supposed to receive dead — or inactivated — anthrax samples for research use.

Spokesman Col. Steve Warren says the Pentagon is working with the Centers for Disease Control and Prevention to retrieve the samples.

He says the government has confirmed one shipment contained live spores and suspects eight others did, too. Warren says the government believes there are no risks to the public.

The live spores were shipped from Dugway Proving Ground in Utah — a Defense Department facility — to government and commercial labs in Texas, Maryland, Wisconsin, Delaware, New Jersey, Tennessee, New York, California and Virginia.

Contact with anthrax spores can cause severe illness.