Police say man who choked on his food while driving caused a chain reaction that led to a fireball exploding over a Walmart in southwestern New Mexico. The Deming Headlight reports 61-year-old Robert Sheppard told police he was eating as he drove Saturday in front of the Walmart Superstore in Deming and that he began to choke, causing him to lose control of his pickup truck. According to police, the pickup, traveling at a "high rate of speed," struck an SUV and then a propane tank attached to a grill in front of the store. Witnesses reported seeing a massive fireball that extended over the roof of the store. Three people were injured, including the person operating the grill.