23:37 Hours Co#1 was dispatched across from 15 South Chestnut St for a reported working structure fire. Chief 1 (Dugan) went enroute and was advised by county of numerous calls advising a working fire. C-1 a.o.s to find heavy fire on side B of the structure spreading into a business beside it. C-1 requested a 2nd alarm which brought in multiple multi aid and transfer units. Crews made an interior attack and within 10 mins had to evacuate due to the roof of the fire building collapsing in. All units went exterior with 4 truck company's operating. Fire had spread into the adjoining ASK business and collapsed the roof of that structure. Once crews had a knock on the bulk of the fire crews went back to interior operations. Thanks to all the multi aid that assisted. Special thanks to Dauphin Engine 35 (Linglestown) for standing by.