Abstract: At 2:45 p.m. on June 26, 2018, Employees #1 through #6, employed by a heating and air conditioning contractor, were working at a multiemployer construction project, an addition to a hospital. One employee was working on vent pipes on the roof near the hospital's central utility plant. Others were in the utility plant's boiler room and purging air from gas lines. They did not use a combustible gas detector, instead relying on their sense of smell to detect the odorant in natural gas. There was an explosion of natural gas. One employee was struck by debris from the explosion and thrown into a wall. Others incurred other injuries. This incident resulted in one employee being killed and five requiring hospitalization.