On September 18, 2012, 22 workers died when a gas leak from a Kinder Morgan pipeline at Reynosa, Tamaulipas, Mexico sparked an explosion which became a fireball that overtook workers running for their lives, lead plaintiff Javier Alvarez del Castillo said in his fourth amended complaint, "They were engulfed in fire that burnt and singed every inch of skin from their head to their ankles, taking every bit of hair from their head, laying the plaintiffs 'skinless,' like skeletons bare to the bones, with in most cases only their footwear attached to the only portion of their body not reduced to skeleton." He blamed Kinder Morgan for not adding enough of the odorant methyl mercaptan to the gas. (Natural gas is odorless, so energy companies add the sulfur compound to make leaks smelly and therefore noticeable.) "A gas company may be liable if facts show that it fails to act reasonably after having notice of defects in the pipes through which gas flows," the ruling states, citing the Texas appellate court case Entex, a Division of NorAm Energy Corp. v. Gonzalez. On July 13, 2016, a U.S. Federal Court ruled that only Kinder Morgan and not any of the other companies originally sued by plaintiffs’ groups should face the charges of gross negligence and negligence. The cause of the leak was a valve that apparently failed as workers performed routine testing, but gaps remain in what is known about the events that led up to the Reynosa explosion.