WASHINGTON (AP) — Envelopes containing ricin — a deadly poison — were mailed to law enforcement agencies in the Rio Grande Valley, according to a law enforcement official who spoke with the Associated Press.

The official did not say which agencies were sent the envelopes but said they are believed to have been mailed by the same person who sent one to the White House.

One of the envelopes was sent to the police in Mission, said Investigator Art Flores, a spokesman for the Mission Police Department. He said no one was hurt and that the envelope was in law enforcement's custody. He declined to comment further.

An envelope containing ricin was also intercepted en route to the White House. A woman accused of sending the letter to the White House was taken into custody by U.S. Customs and Border Protection officers at the Peace Bridge border crossing near Buffalo and is expected to face federal charges, three law enforcement officials told The Associated Press. 

Her name was not immediately released, but the woman was expected to appear in federal court in Buffalo on Tuesday. 

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. 

Envelopes containing ricin were also mailed to law enforcement agencies in the Rio Grande Valley in South Texas, according to another law enforcement official. The official did not say which agencies were sent the envelopes but said they are believed to have been mailed by the same person who sent one to the White House.

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

The Royal Canadian Mounted Police in Quebec confirmed Monday there is a police investigation taking place on a street in St-Hubert, Quebec, related to the contaminated letter sent to the White House.

The home is connected to the woman who was arrested at the border and although authorities have yet to determine whether she actually lived in the house, "there is a clear link between her and this residence," Royal Canadian Mounted Police Cpl. Charles Poirier said. 

There have been several prior instances in which U.S. officials have been targeted with ricin sent through the mail.

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. 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.

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Associated Press writer Jake Bleiberg in Dallas and Rob Gillies in Toronto, Canada, contributed to this report.

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