Three workers died in a gruesome accident at a New York City waste transfer station Monday afternoon, when they fell into a well filled with deadly hydrogen sulfide gas.

The men were apparently overcome by the hydrogen sulfide when they began the dangerous and difficult job of vacuuming the 18-foot-deep well at the Regal Recycling Center in the Jamaica section of Queens. The waste transfer station at this site is used for the temporary storage of solid waste until it is transferred to a permanent disposal site.

The victims included a father and son, Shlomo and Harel Dahan, as well as another worker, Rene Francisco Rivas. The men died when they descended into the well in turn, beginning with the 23-year-old Harel Dahan. According to news reports, the young man was trying to unstop a drain with a long pipe plunger and fell into a four-foot cesspool when he was overcome by the hydrogen sulfide.

His father, 49-year-old Shlomo Dahan, then followed in an effort to rescue the son, but was also overcome by the fumes and fell. The elder Dahan, born in Israel, was a contractor who owned a small business that cleaned storm drains. He had been hired by the Regal firm to clean the well.

Rivas, 52 years old, was a native of El Salvador. He tried to save his fellow workers by following them, and perished as well.

While it was likely that the men were killed by the toxic fumes, they may have drowned after being overcome and incapacitated by the gas. Friends indicated that they were probably unaware of the danger of the sulfide gas. A Queens County deputy assistant fire chief was quoted in the local press as saying that concentrations of 50 parts per million of hydrogen sulfide would be lethal within 10 minutes, and that measurements inside the well later showed a level four times that, at 200 parts per million.

A neighbor of Rivas’s told reporters that he saw him going to work that day. He said he rarely saw him because of his long hours. “This man always works, every day he goes to work.

Oscar Rivas, the son of the victim, said that “he saw two men fall into the hole, and he jumped in to try and help them. He was always like that, always helping people. He was a good person.”

Shlomo Dahan was married and the father of two other sons and a daughter.

The tragedy was not purely accidental, in the sense that safety violations, including inadequate training for dangerous work, were undoubtedly factors. These are the kinds of incidents that have been happening all too often, especially but not only in the city’s construction industry, as profit considerations lead to potentially dangerous and in some cases fatal consequences, most often involving lower-paid and immigrant workers.

The Regal facility had been fined the sum of $1,500 by the federal Occupational Safety and Health Administration in 2006, after the death the previous year of another Salvadoran worker, 46-year-old Effraine Calderone, who was crushed when the driver of a Caterpillar tractor put the machine in gear and rolled over him. The company was facing additional fines from inspections this year that led to citations for unsafe floor and wall openings and holes, and inadequate respiratory protection and medical services, among other problems.

The waste transfer station is located in an area of mixed residential and industrial use. The street on which it is located is dominated by obviously dangerous environmental hazards.