A facility custodian accidentally mixed a toxic combination of chemicals at the Wisconsin Department of Corrections building on Tuesday. The Madison Fire Department says they responded to a report of a chemical spill at about 5:30 p.m. at the DOC building at 3099 East Washington Ave. Paramedics were added to the call when the Dane County 911 Communications Center learned somebody in the building was having trouble breathing. Officials say a facility custodian was preparing to clean the toilets when she mixed lemon bleach and toilet bowl cleaner together. This combination of cleaning chemicals is known to be toxic and even deadly. According to the incident report, the custodian poured the solution down the drain of a slop sink and evacuated the building when she realized what happened. Paramedics evaluated the custodian as firefighters entered the building to assess remaining hazards inside, according to the Fire Department. There was a slight odor of chlorine, but firefighters determined the hazard had been controlled.