Three people have been charged with second-degree murder after a 5-year-old boy was killed when a hyperbaric chamber exploded at a medical facility in Michigan earlier this year, officials announced Tuesday.

Two other people were arrested Monday and also are expected to be arraigned in the child's death, police said.

Troy police say Tamela Peterson ran away when asked for her cellphone after Thomas Cooper died in a hyperbaric chamber fire at the Oxford Center.