Four people have been arrested after a 5-year-old boy was killed in a hyperbaric chamber explosion in Troy, Michigan. The Troy Police Department confirmed that the arrests occurred Monday morning. They are scheduled to be arraigned on Tuesday.

Three people were charged with second-degree murder and a fourth person was charged with involuntary manslaughter in the death of Thomas Cooper, 5.

Troy police said arrests were made Monday in connection with the Jan. 31 explosion that killed Thomas Cooper. The boy, 5, was inside the chamber when it exploded.