Abstract: At 2:30 p.m. on June 11, 2020, Employee #1 removed the inspection door to the re-metalizing box on the Yoder Mill to check the quality of the aluminum deposit on the steel tubing and noticed a glow in the exhaust duct. Employee #1 notified Employee #2, and they both went to the rear of the Yoder Mill. Employee #1 and Employee #2 were facing each other and talking. Employee #2 was closest to the exhaust duct and had his back to the exhaust duct when a flash fire occurred in the exhaust duct. Employee #1 sustained second degree burns to his face and left arm. Employee #2 sustained third degree burns to his back, chest, both arms and both legs. Both employees were hospitalized.