A fire that destroyed a Milwaukee elementary school on June 30 was caused by rags soaked with cleaning liquids that spontaneously combusted inside the building, according to a fire department investigation. Students who were studying at Lincoln Avenue School will move to the nearby Casimir Pulaski High School this school year. Many Milwaukee school buildings do not have fire sprinkler systemsLipski said the school building on the city’s south side is between 107 and 109 years old. Cassellius said that of the district’s 139 school buildings, 22 have full or partial fire sprinkler systems installed. Cassellius said it would cost between $1 million and $2 million to retrofit sprinkler systems in school buildings that do not have them now.