Metra said that trains will be stopping at the station Thursday despite the fire, but that the ticket office is closed.
Firefighters responded shortly after 11 p.m. to the fire. According to authorities the fire started in a storage room where the furnace was located.
On Friday, fire investigators said the fire was accidental and appeared to have been related to a heater unit that was malfunctioning.
Authorities said no one was in the building at the time of the fire.
On an average week day more than 1,500 people use the station.