A hazardous materials team was called Monday to investigate a suspicious letter sent to the home of Republican Sen. Susan Collins, police officials said.

Police and fire vehicles were parked outside her home, and several people in hazmat suits were seen entering the home. Yellow police tape was wrapped around the perimeter of the property.

The senator’s husband, Thomas Daffron, was at home but Collins wasn’t there at the time.

“Her husband is at the house now, and she’s on her way home,” said Annie Clark, spokeswoman for Collins.

Critics have vowed that Collins will for voting to confirm Supreme Court nominee Brett Kavanaugh. But it was unclear who sent the letter or why.

Bangor Police Sgt. Wade Betters said that the public isn’t believed to be in any danger.

Contents of the letter were being analyzed by law enforcement officials. Further questions were referred to the Capitol Police Department in Washington, D.C.

(AP)