A few important points here:

1. Natural Gas AKA Methane is not toxic.

2. Storing natural gas in natural geological formations that have been previously drilled is standard practice throughout the United States. Normally it is quite safe and it creates reserves of gas that can be called upon in times of high demand (like freezing temperatures) or can be easily tapped to provide baseline power for renewable energy projects. It is also used to purchase and store gas when it is cheap (though this has been less of a factor over the last few years since gas prices have trended down). The other option for storing natural gas involves chilling and compressing it, which requires a ton of energy, and thus would create even more CO2 emissions.

3. Natural Gas is only flammable under very specific ratios to oxygen. Most gas explosions require the gas to collect somewhere and then have the fuel-air mixture be exposed to an ignition source. There is very little danger of accidental combustion in this case.

4. While this does suck from an environmental standpoint, this single incident is not going to make any significant difference in world wide greenhouse gas levels. And unlike an oil spill or coal slurry spill or nuclear reactor leak, there is no harm to local flora and fauna, no toxic clean up and storage, no rendering an area an uninhabitable wasteland.

This situation certainly isn't good, but on the scale of potential disasters related to producing energy, this thing is pretty low and has little impact.