Abstract: At 9:00 a.m. on May 29, 2020, Employee # 1 and 2 coworkers discussed entry into a manhole to clear a blockage. Employee # 1 entered into the manhole without personal protective equipment, without training, and without performing any air quality testing. Employee # 1 successfully placed the line to clear the blockage and began to climb out. Before he could exit, he was overtaken, likely by hydrogen sulfide, an oxygen deficient atmosphere and lost consciousness. The manhole contained approximately two feet of standing water. When the others realized that Employee # 1 was unconscious, Coworker #1 tied a ratchet strap around a fence adjacent to the manhole entrance and around his waist. As Coworker #2 contacted emergency services, Coworker #1 entered the 17 foot deep manhole. Coworker #1 reached Employee # 1, lifted him out of the water, but was unable to pull him out of the manhole. Coworker #1 began climbing out of the manhole but lost consciousness prior to reaching the top. Coworker #2 pulled Coworker #1 up several feet allowing Coworker #1 access to fresh air. He regained consciousness and began climbing out of the manhole with assistance from Coworker #2. Employee # 1 could not be rescued. Coworker #1 was taken to the hospital for assessment of his injuries (cuts and bruises). After more than one hour and positive pressure ventilation had been implemented in the manhole, atmospheric monitoring performed by the fire department indicated that oxygen levels were at 20.4% and hydrogen sulfide was present at 5.5- 6 parts per million. Employee # 1 was killed. Coworker #2 was provided basic screening for injury and illness by emergency services at the site as he had momentarily entered the manhole during his rescue of Coworker #1. He was not hospitalized.