Box 513, Companies dispatched for alarms activated in the building. District 1 arrived to a 4 story brick, nothing evident. Upon making entry, Ladder 6 received reports of a fire on floor 3. Conditions quickly escalated, and companies found heavy fire in a 3rd floor apartment. Exterior companies began reporting fire visible through the roof, far away from the original fire apartment. Companies on the top floor found advanced fire in the walls and cockloft spreading above multiple units. 2nd alarm transmitted.