A 24-unit apartment complex off the Beltline was evacuated Sunday because of high levels of carbon monoxide. Madison fire officials said firefighters were dispatched to 213 West Beltline Highway just before 2 p.m. after MG&E detected elevated levels of the deadly gas while on a service call. Firefighters confirmed carbon monoxide levels above 200 parts per million in the boiler room and levels in the high 80s ppm in some hallways. According to an incident report, MG&E had already shut off the gas by the time firefighters arrived at the scene. Crews worked to ventilate the building and knocked on residents’ doors to get them to evacuate the building until carbon monoxide levels were safe.