A methane leak in Southern California has forced thousands of people from their homes. Although the gas first began spewing from a leaky underground well in October, the gas company only recently identified the source of the leak. Now, officials with the company say it could be months before the methane leak is stopped. But what exactly caused the methane leak in the first place, and how will it affect those in the surrounding areas? Here are five things to know about the Southern California methane leak.