Though the fires are alarming, one must realize that hundreds of thousands of vehicle fires occur in the US every year. Electric Teslas, like any vehicle (including those with an internal combustion engine), are not immune to catching fire in certain situations. Here's Musk's take on the issue: "[The Model S] is about five times less likely to have a fire than an average gasoline car," he reportedly said Tuesday at the New York Times' DealBook conference in New York.
The first of the aforementioned fires occurred in Seattle and started in the battery pack after the Tesla hit a piece of road debris. The second fire occurred in Merida, Mexico, after the driver, who was speeding in his Model S, reportedly struck a raised pedestrian crossing, launched into the air and then crashed into a wall and tree. The third Model S ignition occurred after the driver ran over a tow hitch in Smyrna, Tenn., and - similar to the Seattle fire - damaged the undercarriage of the car where the battery is located.