Ludhiana, May 1 (PTI) A five-member Punjab Police Special Investigation Team (SIT) will probe the Giaspura locality gas leak incident here in which 11 people died after allegedly inhaling toxic gas, officials said on Monday.

The tragedy struck the densely populated area in Punjab's industrial hub on Sunday. District authorities said the locality underwent a night-long decontamination process, involving putting caustic soda in drains and sewerage lines to counter the hydrogen sulphide build-up.

Teams of the Punjab Pollution Control Board are looking into the possible reasons behind the build-up of the poisonous gas in the sewer that might have led to the incident, the officials said.

Traces of the gas are no longer present in the area, they added. Hydrogen sulphide, also called sewer gas, is poisonous and smells like rotten eggs. It can lead to unconsciousness and death.

Speaking to the media here, Ludhiana Police Commissioner Mandeep Singh Sidhu said the SIT will be led by Deputy Commissioner of Police (Investigation) Harmeet Singh Hundal.

He said the team would investigate if any industrial unit dumped waste in the sewerage line. Sidhu said police would seek cooperation of the Punjab Pollution Control Board on this, and if its officials do not cooperate, action would be taken against them too.

The officials earlier said the poisonous gas might have been released after some chemical was disposed of in the sewerage in the area. The authorities are scouring through CCTV footage to confirm this.

A magisterial inquiry has already been ordered, and police have registered an FIR under IPC section 304 (culpable homicide not amounting to murder) against unidentified persons.

The incident came to light on Sunday morning when some people, who had come to a grocery store in the Giaspura locality, fainted. Four died on the spot, while the others were rushed to a hospital.

All the 11 deceased belonged to Uttar Pradesh and Bihar. Giaspura has a very high migrant population. Several industrial and residential buildings are located there.

Among the dead are three members of the family that owned the store and five from another. The administration has announced Rs 2 lakh compensation each for the family of the deceased and Rs 50,000 each for those who were taken ill in the incident.

Meanwhile, Ludhiana Deputy Commissioner Surabhi Malik on Monday said the area has been decontaminated. Teams of the National Disaster Response Force and the municipal corporation took readings of the ambient air quality in the area throughout the night, she told PTI, adding, “Hydrogen sulphide was no longer detected in the air.".

The teams also checked the manholes in the area at frequent intervals. "During the night, the level of hydrogen sulphide in the manholes was high but it has gone down after the chemical decontamination process," she said.

A pollution control board team is mapping the industries located in the area to check the inlet and outlet of their water, the deputy commissioner said.

She said the cordoned off area has been reduced from a radius of 250 metres to 25 metres as the air was found to be alright. The authorities had on Sunday cordoned off the area after the gas leak. PTI CHS SUN.