I was backing out of a tandem parking spot in a private garage and got too close to a pillar, and tried to pull forward into the spot. It felt like the car got snagged on the pillar, but while pulling forward slowly, the gas pedal snapped off and the car accelerated quickly and uncontrollably. I was able to avoid hitting other cars but drove straight into a concrete wall despite immediately braking. I'm relatively uninjured, but if it had happened in a less controlled environment and/or I hadn't reacted as quickly, there could have been serious injuries to myself or others. There was no indication of an issue prior, and the car is currently in storage with my insurance company and will be appraised next week. I have photos of the broken pedal.