CONCORD, N.H. (AP) — The New Hampshire Democratic Party Office has been evacuated because of a suspicious package, police said.

At least three employees were present when the package was found Monday afternoon, the Concord Monitor reported. Police told the newspaper that first responders checked at least one of those employees for possible exposure to a substance in the package, but no injuries were reported.

The New Hampshire office tweeted that the employee was treated “merely as a precaution.”

“This afternoon, we alerted authorities immediately upon finding a suspicious package at the NHDP Headquarters,” state Democratic Party Chairman Ray Buckley said in the tweet.

It’s unclear what might have been in the package.

A spokeswoman for the Democratic Party, Sarah Guggenheimer, in an interview with the newspaper declined to detail the nature of the package, how it was delivered or what prompted suspicion. She cited a desire to protect sensitive details while authorities investigate.

The building in Concord is on lockdown and traffic is being diverted away from the area. Police, fire crews and a state hazmat team are on scene. Federal law enforcement is involved in the investigation.

The party relocated a planned Monday evening meeting to an off-site location shortly after the package was discovered, Guggenheimer told the newspaper.