According to the Associated Press report, initially just one worker had gone into the shaft. His failure to return prompted the other two to go in and find out what had happened to him and they suffered the same fate, falling through the shaft and into the well itself.

The men had been hired to clean out a basin designed to catch water and waste from the transfer station, where rubbish is sorted for recycling. The entrance to the basin is through a manhole around three feet wide by 18 feet long.

Officials have said that the men were likely to have been overcome by hydrogen sulfide - a toxic gas created by water and decomposing rubbish that is common in wells like the one they were cleaning. About 100 parts per million of the gas in the air is considered highly dangerous; rescue crews at the Royal Waste Services waste transfer station, where the incident occurred, were getting readings of 200 parts per million.