A fire broke out at Algonquin Middle School after three kids were playing with fireworks on the southwest side of the building Saturday, Des Plaines police said.
The three -- one 13-year-old and two 12-year-olds -- have not been charged with a crime as of Saturday night, police said.
Des Plaines fire officials were investigating the suspicious fire Saturday afternoon at the school, 767 Algonquin Road.
The blaze caused an estimated $20,000 in damage to the building, said John Pahlman, Des Plaines Elementary School District 62 maintenance and operations director.
The first firefighters who were called to the school about 4:25 p.m. discovered a large fire on the school's south exterior, Des Plaines Fire Chief Alan Wax said.
Based on a preliminary investigation, the fire was suspicious because there was a report of children in the area before the blaze, Wax said.
Crews were able to put the fire out in minutes, and it did not spread into the building, Wax said.
The fire appeared to start in plastic crates outside two steel doors at the entrance to a mechanical and receiving room. No one was inside the school at the time.
Des Plaines police continue to investigate.