A package containing the poison ricin and addressed to President Donald Trump was intercepted by law enforcement earlier this week, U.S. media reported Saturday.
Tests confirmed the presence of ricin, a poison found naturally in castor beans, according to local reports.
Investigators are looking into the possibility that the package was mailed to the president from Canada, CNN reported citing a U.S. law enforcement official.
Mary-Liz Power, chief spokeswoman for Canada's Minister of Public Safety Bill Blair, said in a statement that Canadian law enforcement officials are working closely with their U.S. counterparts, according to CNN.
The U.S. Centers for Disease Control and Prevention says it would take "a deliberate act to make ricin and use it to poison people" and that no antidote exists for the poison, which can kill a person within 36 to 72 hours of exposure, according to USA Today.