WALTHAM, MA - A caller at 1 First Avenue in Waltham reported an electrical explosion on February 14th around 11:30 A.M. Waltham Fire dispatched Engines 2 and 7, Rescue 1, Tower 1 and Medic 1. Engine 7 arrived and reported smoke coming from a side door. Firefighters were unable to enter the building because of a blown transformer. The building was a data storage facility with a large server room. Deputy Bob Lahey requested a working fire which brought Squad 5 and Medic 2. Prior to the power being turned off, Ladder 2 was special called. Once the power was shut off, the fire was put out with extensive overhauling. Companies were on the scene for about three hours. The State Fire Marshal was investigating the incident.