Investigators want to know what started the fire at a commercial building Tuesday evening.

911 calls started coming in just before 9:30 p.m. from neighboring business owners. Flames were reported visible from the building's windows in the 13400 block of NE 20th Street.

Bellevue Fire crews responded within minutes and started their attack. More than twenty units from different Eastside fire departments responded to assist as the fire grew in intensity.

Nine business spaces suffered damage by fire and smoke. Early damage estimates reach 1 million dollars.

Bellevue Fire says the building was not equipped with fire protection systems.