At least two packages suspected of containing the poison were shipped to the headquarters of the US Defense Department. Authorities are investigating who sent the packages after they were intercepted during screenings.
The FBI on Tuesday launched an investigation into packages believed to contain the deadly poison ricin that were sent to someone at the Pentagon.
Pentagon spokesman Chris Sherwood said at least two packages were intercepted at a delivery facility on Pentagon grounds and not at the defense department's main five-sided building.
What we know so far:
Ricin is a poison derived from castor beans that can easily be overlooked as the cause of death at autopsy. There is no known antidote to ricin but emergency medical care immediately after exposure can prevent death.
In 2013, several letters containing ricin were sent through the US Postal Service, including one intercepted in Washington DC and addressed to former President Barack Obama.
ls/msh (AFP, AP)