An arson investigation is underway after a partial evacuation at the Pen Centre.
St. Catharines Deputy Fire Chief Dave Upper says investigators combed through the scene yesterday.
"The Ontario Fire Marshall and The Arson Investigation Task Force are both looking into the cause and origin of the fire."
The suspicious fire broke out inside the Dollarama at about 5:30 p.m. on Thursday.
No one was hurt in the fire which was quickly suppressed by the sprinkler system, but thick smoke did cause a partial evacuation.
Damage is pegged at around $200,000 - most of that can be attributed to merchandise hit by the sprinkler system.