In the Medicine Hat explosion, the responders made a hole on the floor but a fireman felt a rush of natural gas and warned all the other firemen to vacate the area.
When the first responders saw where the fire was coming from, they started to chop a hole in the floor of the building to locate the source. A fireman, B. Ringler, was using an axe and had just opened a hole in the floor when he felt a sudden rush of natural gas. Realizing the danger, he yelled to the other firemen to get out of the building. 
