Abstract: At 7:45 a.m. on September 7, 2021, Employee #1, a manager, and Employee #2, a technician, were working on a historic property. Employee #1 arrived first and turned on equipment in the buildings. He reported smelling propane gas outside which became stronger as he entered the house. He opened doors and windows to ventilate the house before going to another building. He reported the potential gas leak to his coworkers and called the gas company. Employee #2 was delivering a propane tank when he was dispatched to the house. At approximately 7:15 a.m., Employee #2 arrived on site and was met by Employee #1. Employee #2 stated the odor was not overwhelming and he inspected the 1,000-gallon and 500-gallon underground propane tanks to perform leak tests. Employee #2 shut the gas off to both tanks. The 1,000-gallon tank supplied gas to the corporate building, and the 500-gallon tank supplied the house. Employee #1 reported that the meter for the 500-gallon tank was at zero. After shutting off both tanks, Employee #2 followed Employee #1 into the basement where the tank had been supplying gas to the furnace and water heater. In the basement the gas odor grew stronger. Employee #2 said they should go outside. Once outside, Employee #2 performed a leak test and checked pressure gauges and the regulator and removed gauges on the tank. Employee #2 installed a presto tap on the second stage regulator and turned his back to get another tool when the building exploded. Employee #2 was thrown approximately 30 feet and was struck by flying glass and wood. He noticed a fire had started and he retrieved a fire extinguisher. A coworker was already using a fire extinguisher until the fire department arrived. Employee # 1 was hospitalized to treat a loss of taste, swallowing issues, memory loss, and leg and head injuries. Employee #2 was hospitalized to treat bruising, cuts, and scrapes to his foot, arm and head.