Boothbay Harbor, Boothbay and Southport fire departments responded to a sprinkler alarm and a call about smoke coming from the back of the House of Pizza in the Meadow Mall on Rt. 27/Townsend Avenue at 3:25 a.m. <Tuesday> morning. Boothbay Harbor Fire Chief Nick Upham said that when crews arrived, sprinklers were active, a fire was forming on the back wall and smoke was filling the restaurant. Upham said the cause of the fire was undoubtedly electrical, with damage resulting to the back wall and water damage throughout. A clean-up crew has been working this morning at the restaurant and it is uncertain when the restaurant will open again. This story will be updated.