A "tall mechanism with lots of water coming out" is generally an indication that the firefighters have gone into defensive mode and have given up on saving the structure. Cutting the roof is standard practice to vent the horizontal heat and flames vertically and then advance a hose line into the building to extinguish the fire. My guess is there was not major damage however because it's a food store, the stock will have to be replaced, hello insurance company, just what they need!