Early Tuesday morning, Valhalla FAST was requested to Mt. Kisco for a 2-Alarm fire. Valhalla was called in as the 3rd FAST due to the commercial building fire. When the FAST arrived they were briefed by command and the Yorktown Heights FAST. The Valhalla and Yorktown FASTeams split the FAST duties to ensure a safe scene for the crews working. Once the fire was under control Valhalla FAST was put to work checking adjacent building for smoke and carbon monoxide levels. Crews vented the structures that had high levels of CO. Once all readings were down to acceptable levels, Valhalla was released by command.