Chemical-soaked rags that spontaneously combusted caused the five-alarm fire that destroyed Lincoln Avenue School in Milwaukee on June 30, the Milwaukee Fire Department announced Monday.Milwaukee Fire Chief Aaron Lipsky announce d the findings during a press conferece Monday alongside Milwaukee Mayor Cavalier Johnson and Milwaukee Public Schools Superintendent Brenda Casellius."No evidence to suggest this was an arson fire," Lipski said. Lipski said there was "human error involved," adding that rags used by janitors cleaning the school were tossed into a garbage can.What caused the fire Surveillance video provided by Milwaukee Public Schools proved critical to the investigation, Lipsky said, because fire investigators were unable to enter the unstable building.The video shows custodial workers who were working during summer break to clean the building place chemical-soaked rags into a plastic garbage can at the end of the day. Lipsky said the chemical-soaked rags underwent small chemical reactions that produce heat and that rags placed on top confined that heat, causing temperatures to rise further in a cycle that ultimately resulted in spontaneous combustion.More than 100 firefighters battled the blaze from early morning well into the afternoon, knocking out power in the neighborhood for a short time. No injuries were reported.MPS policy changes Casellius said MPS reviewed its own surveillance video and took immediate action before investigators completed their work.New protocols require custodial staff to place rags containing oils or other chemicals in approved metal containers which have been distributed to all schools at the end of every shift. MPS is also limiting the application of oil-based chemicals to days when temperatures are below 85 degrees and requiring employees to verify at the end of each shift that all fire doors, room doors, and required windows are closed and secured."We have done training of all of our custodial staff," Casellius said.When asked whether any custodial staff faced disciplinary action, Casellius said MPS would follow its normal internal investigation process but declined to discuss personnel matters publicly.Demolition and insuranceMPS received an initial insurance payment of $5 million to fund demolition of the remaining structure. Casellius said the district is requesting bids from demolition contractors and that work would begin in the weeks following vendor selection. She estimated the cost to replace an elementary school at approximately $50 million.Students and familiesAll Lincoln Avenue programming and student supports will continue at Pulaski High School when the school year begins September 1. Transportation is available for students who need it, including families who previously walked to Lincoln but are not close enough to walk to Pulaski.This is a developing story and will be updated.Its about time to watch on your time. Stream local news and weather 24/7 by searching for TMJ4 on your device.Available for download on Roku, Apple TV, Amazon Fire TV, and more.Report a typo or error // Submit a news tip ...read more read less