At least two packages suspected of containing the deadly poison ricin have been sent to the Pentagon this week.
Defense Department spokesman Chris Sherwood said the suspicious packages were addressed to someone in the Pentagon, the headquarters of the United States Department of Defense, in Washington, DC.
They were found at a delivery facility on the Pentagon grounds but not inside the main building that includes the offices of the defense secretary.
“As part of the screening process, [authorities] recognised some suspicious packages,” Mr Sherwood said.
He stressed that authorities were still waiting for confirmation that the packages contained ricin.
Pentagon police referred the matter to the FBI for investigation.
“FBI Special Agents took possession of two suspicious envelopes that had been screened at the Pentagon mail facility. Those envelopes are currently undergoing further testing,” the FBI said in a statement.
All mail received at the Pentagon’s screening facility Monday was “placed under quarantine and poses no threat to Pentagon personnel,” said Pentagon spokesman Colonel Rob Manning.
Ricin is a poison found naturally in castor beans. If the beans are chewed and swallowed, the released ricin can cause injury.
According to the Centers for Disease Control and Prevention, ricin has the potential to cause death under certain circumstances if it is made into a partially purified material or refined.