Sanford and Seminole County firefighters are responding to reports of a gas leak Wednesday evening. Firefighters said they are at the scene of a leaking high-capacity liquid propane tank. They said crews are doing a “burn-off” to reduce levels of the fuel. Seminole County deputies and utility workers are also assisting at the scene. Firefighters said a gas tanker is at the scene to help offload propane from the leaking tank.