Four Japanese workers are dead after falling into a manhole Saturday during a sewage pipe inspection in Saitama Prefecture in northern Tokyo, Kyodo News reported, citing police.
Hydrogen sulfide, which is a toxic, colorless gas, was detected near the site, and police are investigating whether it contributed to the deaths.
Emergency services were alerted around 9.25 am (0025GMT) after one man fell into the manhole in Gyoda, followed by three others who attempted a rescue.
All four, believed to be in their 50s, were unresponsive after falling into the 60-centimeter-wide (24-inch), 12-meter (39-foot) deep manhole, which is connected to a 2.6-meter-wide sewer pipe that was installed in 1981.
At the time, seven city-commissioned workers were preparing for the inspection as part of drainage maintenance.
The inspection was ordered after a massive sinkhole opened at an intersection in Yashio, Saitama, on Jan. 28, swallowing a truck and killing its driver, whose body was recovered in May.
The sinkhole, believed to be caused by corroded sewer pipes, sparked nationwide concern about aging infrastructure and prompted the central government to urge emergency inspections.
