Early this morning Valhalla FAST was dispatched to a working structure fire in the Elmsford district. First arriving crews found heavy fire in the middle unit. Members of the FAST stood by and made ways of egress for the crews inside. A second FAST from Tarrytown Fire Department was called due to the size of the complex. Once Tarrytown FAST arrived the Valhalla crew assisted with checking for extension in the adjacent unit as well as ventilation on the roof. Crews were released soon after.