07/21/2016 - BOSTON, MASSACHUSETTS (SUFFOLK COUNTY) - Around 1345 hours on the afternoon of Thursday, July 21, 2016, Boston Ladder-3 called into Fire Alarm, asking if they had any calls for a building fire on Bunker Hill Street. They reported heavy fire, from what appeared to be the rear porches of the building. Fire Alarm acknowledged that they had received calls and they were striking Box-4165 at Bunker Hill Street at Sackville Street for 284 Bunker Hill Street. Ladder-9 arrived on-scene and immediately requested a second alarm, reporting heavy fire on three floors. Heavy fire and smoke could be seen from a distance from the fire in the Charlestown section of the City of Boston. Shortly after the second alarm was transmitted, a third alarm was requested. The fire which apparently started in the rear of a four story brick and wood duplex occupied dwelling extended to a three-unit apartment building that was adjacent to the fire building, as well as another dwelling. Large embers floated through the dense neighborhood, prompting some residents to take garden hoses to their homes in an attempt to stop the blaze from spreading. A dwelling at 9 Cook Street, approximately 200-yards from the fire building, caught fire, reportedly from embers from the blaze. Firefighters not only had to deal with the heavy fire conditions found upon their arrival, they also battled the extreme heat, with temperatures in the 90's. Five firefighters were transported from the scene to area hospitals, they were all released that day. No civilians reported injuries. Several hand lines were laid up and over ladders to battle the fire from the roofs of the adjacent buildings. Multiple large hand lines and ladder pipes worked the rear of the building, knocking down heavy overlapping fire. The fire ultimately went to six alarms, bringing several mutual aid companies to the scene, in addition to the large Boston Fire Department response to the fire. Rehab for firefighters was provided by the Boston Sparks Association A-10, and the American Red Cross. Numerous Charlestown residents came out and provided firefighters and other first responders with water and other food and snacks. Firefighters remained on-scene throughout the night hitting hot spots and investigating the fire. The cause of the blaze is still under investigation.