An unknown number of people have been killed and well over 100 injured in a massive explosion at a fertilizer plant in the Texas town of West. The incident began with a smaller fire that ignited chemical tanks, causing an explosion that shot flames high into the air and leveled surrounding buildings for blocks in each direction. A police official estimated five to 15 people have died, but the casualty count is expected to rise as day breaks. One initial estimate put the death toll at between 60 to 70 people. Local officials say around a half dozen volunteer firefighters who first arrived on the scene are now missing. Toxic fumes rising from the rubble of the plant have raised health concerns, and about half the town has been evacuated, including a nursing home.