The Punjab Police established a five-person Special Investigation Team (SIT) on Monday to look into the circumstances behind the poisonous gas leak that occurred in Ludhiana's Giaspura neighbourhood on Sunday, which led to the deaths of 11 persons. In addition, the police issued a warning to the PPCB employees that they would be charged in the case's FIR if they refused to cooperate and assist in locating the offender.

On Sunday morning, tragedy hit Giaspura, a densely populated area, when 11 people, including five members of one family and three members of another, allegedly perished after inhaling a deadly gas thought to be hydrogen sulphide. The region, which is filled with businesses and homes, is predominately populated by immigrants from Uttar Pradesh and Bihar.

According to district officials, the area undertook a nightlong decontamination operation that included pouring caustic soda into drains and sewerage systems to prevent the hydrogen sulphide buildup.

Even though it is believed that the gas leak may have originated from a nearby broken manhole, the PPCB and police officials are still searching for answers more than 24 hours after the incident.

Throughout the night, teams from the municipal corporation and the National Disaster Response Force measured the ambient air quality in the region, according to Ludhiana deputy commissioner Surabhi Malik. "No longer was hydrogen sulphide found in the air. Hydrogen sulphide levels in the manholes were high during the night, however they decreased after the chemical cleaning procedure. Investigations are ongoing to determine why there was such a significant buildup of gas in this particular region alone, she said, noting that the cordoned-off area has been reduced from the initial 250 metres to just 50 metres from the event.

Deputy Commissioner of Police (Investigation) Harmeet Singh Hundal will be in charge of the SIT, according to Ludhiana Police Commissioner Mandeep Singh Sidhu. Additional members include DCP-2 Suhail Qassim Mir and ADCP-4 Tushar Gupta. "But if nothing is visible to the eyes on CCTVs, then the onus would be on PPCB to help with police in finding the offender," he added, adding that while police were checking the CCTVs to uncover any hint about the people who dropped industrial trash into the sewer.

"PPCB is the central agency for monitoring industrial activity and pollution." Their responsibility is to investigate any potential wrongdoing by industries. Only PPCB employees are qualified to inform us which industries were and weren't following the rules. What if a certain industry was using an internal connection to dump garbage into sewage? Only PPCB will enable us to contact them. PPCB personnel will also be included in the same FIR if they refuse to cooperate, according to CP Sidhu.

The officials had earlier suggested that a chemical that was dumped in the local sewer system may have caused the emission of the toxic gas. A magistrate's investigation has already been requested, and police have filed a FIR at Sahnewal police station under IPC section 304 (culpable homicide not amounting to murder) against unnamed individuals.