Natural gas explosions can be very powerful.  Had a large gas main rupture under the street about 30 meters from me when I was a kid.  A motorcyclist was riding down the street at the time.  He laid the bike down and I watched it disappear into the hole -- a heartbeat later the fireball bloomed and took out 5 houses around the rupture and knocked me back a couple of meters.  Don't know where the motorcycle ended up, but I think the rider was ok because he was flat on the ground when the gas ignited.

Slush, do you know much damage was done to the building & surrounding area?