Will a building explode if its filled with natural gas?

Seems like the fire department is very busy in US. For the third time in 2 weeks, the fire alarm has gone off in the building. First time was last week when it went off in the middle of the night while I was working late. Everyone just packed up their stuff and went home for the night.

The second time was 2 days ago when it went off during lunch. Everyone grab their food and ate outside the building.

The third time was today. I was meeting Junyong, Kevin and Kelvin for lunch. Downstairs at the reception, A few people ran down and told the receptionist that they smell natural gas on the second floor. 2 mins later, the smell became even more obvious and people started streaming out of the building. Luckily I was off to lunch and didn't have to stand in the raining waiting for security.

Anyway, an hour later. The commotion ended. From asking around, it seems that the some contsruction people where digging nearby and they might and hit a pipe or something. Causing a leak in the building. The security declared that it was safe to enter the building, but everyone was advise to work from home because the smell was still quite strong in the building. Haha, however, not much people listen.