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.

Four people have been charged in the death of a 5-year-old boy who was killed inside a pressurized oxygen chamber at a medical facility in suburban Detroit.

The Michigan attorney general has accused the owner of a medical center and three of its employees of ignoring safety standards to make a profit.