A joint fire investigation task force has ruled the fire at the downtown Subway late Sunday night, which caused an estimated $300,000 of damage, an act of arson.

The investigators this morning discovered multiple points of origin for the fire, according to a news release, as well as several possible ignitable liquids. Law enforcement collected samples and will send them to the state crime lab.

Firefighters responded to the fire just before midnight after a passerby reported seeing smoke coming from the roof of the building. They forced entry and extinguished the flames, which came from the kitchen area. No one was injured.

Two other business share the building with Subway. Baskin Robbins did not appear to sustain any fire damage. However, the businesses share a common roof and attic, and smoke moved throughout the building. Fire investigators are waiting for crews from Baskin Robbins to arrive to determine the level of smoke damage.

The other business, which was unoccupied, also sustained no fire damage, though there was water on the floor.

Subway will remain closed indefinitely for repairs. The other two local Subways, in Wal-Mart and the CUB, will continue to operate.