An early evening fire in a large three story vacant. The fire intially spread to the vacant next door as well. FIre fighters went to work setting up the tower ladder and advancing multiple hand lines to surround the well involved structure. They initially gained access to the interior by way of the second floor porch but as the third floor and roof began to colllapse and the 1first floor became overrun by heavy fire the airhorns were sounded leaving the interior crew scrambling for and exit. All members were accounted for and the crews in the front of the house took the door to gain better access to the heavy fire on the 1st as the tower and crews in the rear continued to pour water on the heavy fire on the 3rd floor. The fire would be brought under control with minimal extension to the exposure.