Pentagon Inadvertently Shipped Live Anthrax to Labs in Nine States No known exposures are known at this time, officials said.

 -- Samples of live anthrax were inadvertently shipped to private research laboratories in nine states and one in South Korea that were supposed to have received dead anthrax samples, the Pentagon confirmed today.

There is no known risk to the general public and there have been no suspected or confirmed cases of anthrax infection as a result of the inadvertent shipment, officials said.

"The Department of Defense is collaborating with the Centers for Disease Control and Prevention in their investigation of the inadvertent transfer of samples containing live Bacillus anthracis, also known as anthrax, from a DoD lab in Dugway, Utah, to labs in nine states,” said Col. Steve Warren, a Pentagon spokesman.

"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," he added. "The DoD lab was working as part of a DoD effort to develop a field-based test to identify biological threats in the environment. Out of an abundance of caution, DoD has stopped the shipment of this material from its labs pending completion of the investigation.

"One sample of Anthrax was also sent to the Joint United States Forces Korea (USFK) Portal and Integrated Threat Recognition Program at Osan Air Base," Warren said. "There is no known risk to the general public, and no personnel have shown any signs of possible exposure. The sample was destroyed in accordance with appropriate protocols."

The samples were shipped on April 30 from the Dugway Proving Ground in Utah to a military laboratory in Maryland. From there they were shipped via a commercial shipper to eight companies with laboratories in nine states: California, Texas, Wisconsin, Tennessee, Maryland, Virginia, Delaware, New Jersey and New York.

According to a Defense official, a laboratory in Maryland detected that their shipment contained live samples and contacted the CDC.

That triggered a response from the Defense Department and other agencies, including the FBI, to trace the shipments to ensure that they were properly secured.

According to CDC spokesman Jason McDonald, a CDC team was at Dugway investigating how the inadvertent shipment occurred.

"At least 18 labs in nine states received sample kits containing 23 marked specimens and 2 controls," said McDonald said. "One of the controls was labeled ‘antigen 1.’ It was this vial that tested positive in one lab in Maryland. State health departments have done risk assessments and Maryland offered antibiotics to four lab workers due to possible exposure. Three of the four workers decided to take the antibiotics."

The DoD routinely sends dead anthrax spores or inactivated spores to research facilities. The official said that military laboratories use commercial companies to ship samples of live anthrax to research facilities, but only with the proper bio-level safety protocols.

The samples all came from a batch of anthrax listed as AG-1. The Pentagon has confirmed that one of the shipments contained live samples of AG-1 and suspects that the others do as well.

ABC News’ Dr. Richard Besser contributed to this story.