“Initial information from the investigation suggests the letter came from Canada,” RCMP spokesman Dan Brien said in a statement.
The RCMP are now working with the FBI on the investigation. Officials have not indicated where in Canada the package may have come from.
Ricin is a toxic substance naturally found in castor beans and often comes in powder, mist or granular form.
Public Safety Minister Bill Blair admitted to the incident in a statement to CTV News.
“We are aware of disturbing reports of packages containing ricin being directed to US federal government sites. Canadian law enforcement agencies work closely with their American counterparts. As this is an active investigation, we cannot comment further, ”Blair’s office said in a statement on Saturday.
This is not the first time Ricin has been sent to the White House. A woman from Texas admitted to sending letters containing the poison to Barack Obama and former New York Mayor Michael Bloomberg in 2013. She was sentenced to 18 years in prison.
In a statement, the FBI said agents were working to investigate “a suspicious letter received at a US government postal service” and that there was “no known threat to public safety.”
With files from The Associated Press