Updated 8:53 p.m. | Republican Sen. Susan Collins will be able to spend Monday night at her residence in Bangor, Maine, after a suspicious letter was received by her husband there.

“Senator Collins’s husband, Tom Daffron, today received a threatening letter that the writer claimed was contaminated with ricin, a highly hazardous substance which was used in a previous attack against the United States Senate,” Collins spokeswoman Annie Clark said in a statement.

Clark said law enforcement was still investigating the source of the letter, as well as testing the substance involved. It was not immediately known if the letter actually contained the poison.

“Mr. Daffron, their dog, and parts of their home were quarantined while the crime lab undertook an analysis of the premises,” Clark said. “The affected areas have now been cleared, and Senator Collins and Mr. Daffron will be able to remain at home tonight.”

In a statement themselves, the Maine senator and her husband thanked the many military, police and fire agencies involved in responding to the incident.

“We are also truly appreciative of the many well wishes that we received today,” Collins and Daffron said. “Our friends and neighbors have been incredibly kind and have even offered to open their homes to us. We feel blessed to live in such a supportive community.”

Multiple local outlets reported on the incident earlier Monday. This is not the first ricin-related scare for the Senate. A Mississippi man was sentenced to 25 years in prison in connection with a series of ricin-laced letters in 2013, including to GOP Sen. Roger Wicker.

Investigators and a hazmat team responded to a call at Collins’ home at 1:39 p.m. Monday, Bangor Police Sgt. Wade Betters told the Portland Press Herald in a statement.

“Currently we have no information to suggest the public at large is in any danger whatsoever,” Betters said.

While Bangor police responded, U.S. Capitol Police in Washington, D.C., was the first agency contacted about the letter. Local investigators will eventually hand the case and follow-up over to the Capitol Police.

Collins, who was widely seen as the decisive vote to confirm new Supreme Court Justice Brett M. Kavanaugh, was not at home when the authorities arrived, local outlets at the scene reported, though her husband was there.  

Watch: Highlights of Susan Collins‘ Speech Confirming Vote for Kavanaugh