WASHINGTON — A woman suspected of sending an envelope containing the poison ricin, which was addressed to the White House, has been arrested at the New York-Canada border, three law enforcement officials told The Associated Press on Sunday.

The woman was taken into custody by U.S. Customs and Border Protection officers and is expected to face federal charges, the officials said.

The letter addressed to the White House appeared to have originated in Canada, the Royal Canadian Mounted Police have said. It was intercepted at a government facility that screens mail addressed to the White House and President Donald Trump, and a preliminary investigation indicated it tested positive for ricin, according to the officials.

The officials were not authorized to discuss the ongoing investigation publicly and spoke on condition of anonymity.

The FBI, the Secret Service and the U.S. Postal Inspection Service were leading the investigation.

In a statement, the FBI said agents were working to investigate “a suspicious letter received at a U.S. government mail facility” and that there is “no known threat to public safety.”

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.

Authorities said the man, William Clyde Allen III, sent the envelopes with ground castor beans to the president, FBI Director Christopher Wray, along with then-Defense Secretary Jim Mattis, then-CIA Director Gina Haspel, Adm. John Richardson, who at the time was the Navy’s top officer, and then-Air Force Secretary Heather Wilson. The letters were intercepted, and no one was hurt.

In 2014, a Mississippi man was sentenced to 25 years in prison after sending letters dusted with ricin to President Barack Obama and other officials.