In a scene that is all too familiar to — and dreaded by — safety professionals, two workers who tried to rescue a colleague at a Montreal-area cosmetics factory died themselves from breathing large quantities of argon gas, The Canadian Press reports.

The Emballages Knowlton plant, in Lac Brome, Quebec, produces and packages products such as makeup and shampoo.

A 30-year-old subcontractor from Montreal died on the scene July 29 after using argon gas to weld inside a large metal tank at the facility. The two would-be rescuers, a 55-year-old man and a 35-year-old woman, died the next day after being taken to a local hospital.

The older man was overcome from fumes after trying to rescue his colleague. The woman, who was trained in first-aid, also fell unconscious after entering the tank.

According to a spokesperson for the Quebec workplace safety board, which is investigating the incident, the welders were not properly equipped to work in a closed space.

"It's certain that there was a shortage of safety equipment," said Antoine Tousignant. "No accident should occur if all the safety rules are followed."