Four workers have died in Japan after falling into a manhole while inspecting sewage pipes, authorities said on Sunday.

The workers, all in their fifties, were checking pipes in the city of Gyoda on Saturday. When one fell down the manhole for an unknown reason, three others tried to save him, eventually falling in themselves, the local fire department told the AFP news agency.

The workers were then retrieved and taken to a hospital where they were pronounced dead, local media reported.

The four deceased were among at least seven workers present at the site as part of a nationwide survey of sewage pipes. They had been ordered to clean the pipes if required. 

An aerial photo shows the rescue scene of workers who fell into a manhole in Gyoda City, Saitama Prefecture on August 2, 2025The manhole was covering a drop of over 10 meters (33 feet)Image: The Yomiuri Shimbun/AP Photo/picture alliance

Why did the workers fall in?

The fire department said rescuers detected hydrogen sulfide, a toxic gas in high concentrations, coming out of the manhole.

Local law enforcement also said the gas had been detected, Japan Times reported, adding that they suspected the workers might have inhaled it.

The city is yet to confirm this.

“Detailed circumstances leading up to the accident are still unknown, so it’s too early for us to say anything about our responsibility,” a Gyoda city official told AFP on condition of anonymity.

Edited by: Darko Janjevic

AloJapan.com