This is a great example of “know your surroundings”! LNG is INVISIBLE, even on the most humid of days, when its at its LEL – meaning, although there is no “cloud” there is a good chance you may be in a flammable atmosphere if your around an accident. These people had no way of knowing the trailer was leaking, but this video shows us how a flammable gas/vapor that is heavier than air (VD>1) can travel quite a ways away from the container and find an ignition source (in this case – a car).