Police investigates the accident.
According to a report from local authorities, the accident occurred at about 9 am when the workers came down a manhole on Tran Van Giau Street for dredging work. The sewer was some two metres deep and the sewage level was about one metre.
Seeing their colleagues falling unconscious in the manhole, some workers on above ground called for help.
A team of 12 rescue workers arrived at the site five minutes later and brought up the five workers. However, one of them, aged 38, had died while four others aged between 22-36 were rushed to the Cho Ray Hospital.
The site has been cordoned off for investigation.
Initial investigations from local authorities showed that the workers might have suffered from methane and hydrogen sulfide gas suffocation.
