Authorities intercept envelope addressed to White House with ricin: report

'At this time, there is no known threat to public safety,' the FBI said.

An envelope addressed to the White House and containing the deadly substance ricin was reportedly intercepted on Saturday, according to reports.

law enforcement official told The New York Times that investigators believed it came from Canada. The letter was intercepted at a government facility that screens mail addressed to the White House and President Trump, a law enforcement official told AP.

The incident occurred just a day after Justice Ruth Bader Ginsburg's death, opening the door to a substantial shift in power on the Supreme Court.

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On Saturday afternoon, the FBI announced it was investigating a package with the U.S. Secret Service.

"The FBI and our U.S. Secret Service and U.S. Postal Inspection Service partners 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 statement read.

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A Navy veteran was arrested in 2018 and confessed to sending envelopes to Trump and members of his administration that contained the substance from which ricin is derived.

According to Mayo Clinic, Ricin is poisonous and can be produced from the waste that results from processing castor beans. There is no vaccine or antidote for the poison.

The Associated Press contributed to this report.