Yesterday's chemical explosion at the Rockefeller Center home of Fox News and the New York Post turns out to have had a sad, ironic cause: a government audit of hazardous materials in the building.

Hazmat investigators were conducting 1211 Sixth Avenue's mandatory annual chemical check when a fire broke up on an upper floor that housed chemicals used for the building's cooling and heating system. The fire was apparently caused when a maintenance crew accidentally spilled a combustible anti-bacterial agent that was used for the heating/cooling system.

Five people were injured. The most serious injuries were a FDNY battalion chief who suffered chest pains and a maintenance worker who suffered a cut to the head.