A "significant" fire at the Vermont office of Sen. Bernie Sanders is being probed as a possible arson, investigators said Friday.

"A significant fire engulfed the door and part of the vestibule, impeding the egress of staff members who were working in the office and endangering their lives," Burlington police said.

"The sprinkler system then engaged and largely extinguished the fire." 

The small blaze resulted in minor property damage and no injuries.

Investigators believe an unidentified male suspect sprayed a possible accelerant on the office door and ignited it before fleeing.

That suspect has yet to be apprehended, according to the Associated Press. Investigators said they are diligently working to establish a possible motive, though they do believe it was arson.

Earlier on Friday, the Burlington Fire Department said that it was notified of the blaze via phone call and discovered a fire set approximately between the vestibule, the elevator, and the entrance door of Sanders' third-floor office.

The office door suffered little fire damage. However, most of the third floor was hit with significant water damage as the offices of Sanders and those nearby were evacuated.