CAMBRIDGE, MA — Almost two months after a ten-alarm fire that tore through a Cambridge neighborhood , the city's fire investigators have pinpointed its cause.

According to fire officials, construction subcontractors working on-site the day of the fire discarded smoking materials, causing the blaze. Whether or not any criminal charges are appropriate remains an open investigation, officials said. Until that question is answered, officials said they are withholding the contractors' names at this time.

The blaze began at an empty home under construction at 35/37 Berkshire Street in the Harrington/Wellington section of East Cambridge. It quickly escalated to 10 alarms and sweeping through the neighborhood. More than 100 residents had to flee their homes, and 18 buildings were damaged, including a multi-unite, low-income housing complex. Numerous cars were also charred by the flames.