The female worker, in a coma, sustained serious hand injuries and broke one of her limbs. She was rushed to North Lantau Hospital in critical condition and was certified dead shortly after.

The four workers fell into the manhole at around 4pm Thursday. Firemen arrived at the scene, and were later joined by their colleagues from the High Angle Rescue Team.

They managed to first rescue two conscious male workers and rushed them to Yan Chai Hospital and Princess Margaret Hospital.

When they saved a third male worker, he was in a coma and sustained leg injury. He regained his consciousness after a while. He was rushed to North Lantau Hospital.

The female worker was unconscious when she was taken out of the manhole.

As of 8pm, one of the workers was fighting for his life, while the other two were in serious condition.

Speaking to media this evening, the Fire Service Department said officers received the report at 4.05pm today, that four workers were trapped in an eight-meter deep, six meters by seven meters manhole, which only came with a one square meter entrance.

Officers found the three male workers were stranded at a work platform six meters above the bottom of the manhole and the female worker lying on the sewage about 0.5 meters above the bottom.

The first worker was rescued after 20 minutes and it took the crew an hour and five minutes to rescued all four workers.

Firemen added that the workers were changing pipes down there when the incident took place. None of the four workers were spotted wearing a safety belt, officers added.

As to why the female worker was lying on the bottom of the manhole, officers said the question awaits further investigation by relevant departments. The cause of the incident has yet to be confirmed.

A total of eight ambulances, 22 firetrucks, 80 firemen and 19 medics, officers from Urban Search And Rescue Team, High Angle Rescue Team and rescue divers were mobilized for the operation.