What sparked an early morning fire on Union Street in Bangor this morning remains under investigation and Bangor Fire is being assisted by an official with the state fire marshal's office.

Fire crews from Bangor, Brewer, Orono and Veazie worked in some pretty tough temperatures to douse the flames.

Initial reports indicated there was no one to evacuate from the two-unit apartment building and Assistant Fire Chief Tom Higgins confirmed the building was vacant when the fire call came in around midnight.

While the cause is under investigation it appears the fire started in the back of the building which city records, as of April of this year, indicate is owned by Marilyn Lau.

An official with the code enforcement office in Bangor says there were no reported problems with the building on file.