LEXINGTON (CBS) – A fire at a Lexington school is under investigation as possibly suspicious.

Flames broke out around 2:30 p.m. at Jonas Clarke Middle School on Stedman Road. The building was not significantly damaged.

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The fire broke out at an outside portion of the school that was under construction.

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Fire extinguishers on the ground at a Lexington school. (WBZ-TV)

Police said they were investigating to determine if the flames ignited when someone lit insulation on fire, but no final determination has been made.

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The State Fire Marshal’s office responded to the school to investigate.