Several people are dead and more than 160 injured following a fire and chemical explosion at the West Fertilizer Plant in West, Texas. Homes and businesses were flattened and a school and nursing home severely damaged. The incident is being treated as a crime scene, according to Sgt. William Patrick Swanton of the Waco Police Department. Priyan Mendis, in the Department of Infrastructure Engineering at the University of Melbourne in Australia, said an "unusual and rare" confluence of factors would be needed to detonate the dry ammonia stored at the plant.