A package containing ricin was intercepted in the White House mail

A package containing ricin was intercepted in the White House mail, a U.S. official familiar with the matter said Saturday. The package appeared to have come from Canada, and no suspects are yet in custody, the official said.

A spokeswoman for the Federal Bureau of Investigation’s Washington field office said the agency along with the Secret Service and the Postal Inspection Service are investigating a “suspicious letter” received at a U.S. government mail facility. “At this time, there is no known threat to public safety,” the spokeswoman said.

Ricin is a poison derived from castor beans and exposure to it can be deadly. According to the Centers for Disease Control and Prevention, if inhaled or ingested, ricin can cause vomiting, diarrhea and respiratory problems. There is no antidote.

If it is ingested, “within several days, the person’s liver, spleen, and kidneys might stop working, and the person could die,” according to the CDC.