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The six people who died at a Colorado dairy farm in August were exposed to toxic hydrogen sulfide gas, authorities said on Thursday, citing autopsies and toxicology reports on the deceased.
According to the Occupational Safety and Health Administration (OSHA), exposure to hydrogen sulfide gas at “very high concentrations can quickly lead to death.”
The autopsy reports did not indicate the circumstances of the deaths.
Hydrogen sulfide is colorless, but has a sulfurous smell, similar to rotten eggs. OSHA warns that those who have breathed in enough hydrogen sulfide to become unconscious but survive can still struggle with long-term health effects, such as headaches and poor attention span.
SIX DEAD IN DAIRY ACCIDENT IN RURAL COLORADO PLAINS AREA, OSHA INVESTIGATING
A sign stands at Prospect Ranch outside of Prospect Valley Dairy east of Keenesburg, Colo., on Aug. 21, 2025. (Chris Bolin/Denver Post via AP, File)
The deceased have since been identified as Ricardo Gomez Galvan, Noe Montañez Casañas, Carlos Espinoza Prado, Jorge Sanchez Pena, Alejandro Espinoza Cruz and Oscar Espinoza Leos, who was just 17 years old at the time of his death. Cruz was the father of Leos and Prado. The men were also related to Pena through marriage, according to Jolene Weiner, chief deputy coroner for Weld County.
The dairy at Prospect Ranch where the six people died was located in a rural area near Keenesburg, Colo., which is less than 40 miles northeast of Denver.
When the deaths were reported in August, authorities quickly assessed that gas exposure was the likely culprit. It was then up to investigators to determine what kind of gases possibly played a role in their deaths.
“We are investigating these deaths as the possible consequence of gas exposure in a confined space,” Weiner said at the time.
A Colorado dairy farm confined space accident left six workers dead in August. (iStock)
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In late August, the bodies of six people — which have since been identified as five men and one teenager — were discovered after an apparent accident. Southeast Weld Fire Protection District officials said crews were dispatched to a “confined space” rescue, where the bodies were found.
The deaths shocked the community, which quickly sprung into action to help the surviving families of the deceased by organizing fundraisers, such as dances and car washes. Several churches also organized memorial events.
Dairy cattle feed at a farm on March 31, 2017, near Vado, New Mexico. (Rodrigo Abd, File/AP Photo)
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“People are in shock. Everybody in the ranching and dairy community knows it’s difficult, hard work and there are accidents,” said Rev. Thomas Kuffel, a priest at Catholic churches including Holy Family in Keenesburg. “But this is very foreign to them, in that accidents are typically one or two people.”
Fox News Digital reached out to OSHA for comment, but a message indicated that they may not be able to respond during the government shutdown.
The Associated Press contributed to this report.