Nobody was injured in a gas leak in Fond du Lac Tuesday morning. Shortly after 11am, the Fire Department was dispatched to a smell of gas reported by a letter carrier. Upon arrival located the smell of gas, but couldn't locate the exact source. Alliant was contacted, and upon arrival with further investigation narrowed down leak to single structure. The surrounding homes were evacuated, and firefighters deployed lines for fire protection, and made entry to structure. Firefighters found high levels of natural gas, and ventilated structure to provide safe environment for Alliant. Firefighters and Alliant worked on scene to locate source. There was no one at home at the time of the call and there were no reported injuries. The Fond du Lac Police Department assisted with scene security and traffic control.