MUMBAI: Four labourers died of suffocation on Sunday while cleaning a water tank in an under-construction building in south Mumbai, officials said.

They had put the death toll at five earlier.

"The incident occurred at Bismillah Space building located on Dimtimkar Road in the Nagpada area around 12.30 pm. Five persons entered the tank and fell unconscious. They were rescued by fire brigade personnel and rushed to JJ Hospital, where doctors declared four dead on arrival," a civic official said.

He identified the deceased as Hasipal Shaikh (19), Raja Shaikh (20), Jiaulla Shaikh (36) and Imandu Shaikh (38), while the fifth person, Purhan Shaikh (31) is recuperating.

An accidental death report (ADR) was registered and a probe has begun to find out lapses, if any, on the part of those who hired the five and whether safety protocols were adhered to, a JJ police station official said.

Action will follow as per the findings of the probe, the police official added.

Fire Brigade, BMC and police personnel are at the site as part of the probe, he said.