Fire officials think equipment failure may have possible caused a four-alarm fire that destroyed a Quincy business on Saturday. Thirty-six firefighters; 28 from Quincy and eight from Boston, battled the blaze that broke out around 2:41 p.m. Saturday at Dependable Cleaners at 320 Quincy Avenue. Due to the intense heat of the fire and the hot weather, firefighters were forced to work under very difficult conditions. Four firefighters– three from Quincy and one from Boston — were treated and released at Quincy Medical Center. Three were treated for smoke inhalation, one for dehydration and a cut that required stitches. The building was deemed a total loss. The business has locations around the South Shore and Boston. Dependable Cleaners was recently named a “Top 100 Women-Led Business” in Massachusetts by the Boston Business Journal and the Commonwealth Institute.