The Health and Human Services building at 200 Independence Ave. SW was evacuated shortly after 10 a.m. this morning after a small electrical explosion occurred in the building. No injuries and no fire resulted from the explosion, which happened in a penthouse electrical room and affected a transformer connected to the building’s A/C system, according to D.C. Fire/EMS spokesperson Pete Piringer. The building was reportedly evacuated as a precaution due to the possibility of a secondary explosion.