The incident took place at 10:35 a.m. Wednesday at Northside College Prep High School. A total of five students were in the area where the gas explosion happened. Two were taken to a hospital with what was described as "serious" face and arm burns. Two other students were taken to a hospital with minor burns and a fifth declined hospital care, the Chicago Tribune said.
Fire sprinklers extinguished the blaze resulting from the blast and the school was evacuated. Six ambulances and a host of police and fire units responded to the school and students stood along the sidewalk outside the building, waiting for officials to clear them to return inside.
Officials said they were not sure what caused the explosion.