Kolkata, June 25 : The death toll in the roof collapse incident at an under-construction warehouse on P2 Transport Depot Road in Kolkataâ??s Taratala reached nine on Thursday morning.

According to government officials, nine workers have died, while 20 others are undergoing treatment at SSKM Hospital. The condition of the two is said to be critical, as per the hospital sources.

The rescue operation continues at the spot to recover a few others who are still trapped under the debris.

So far, five people have been arrested in the incident. They are Gulzar Hossain (Supervisor of Ayan Traders), Kamal Samanta (iron structure manufacturer), Shambhunath Behera (who took the land lease), Dibarak Bhandari (labour supplier and Trimex contractor) and Abdul Hamid (intermediary for approval of construction plans at Kolkata Municipal Corporation).

The investigation team is probing whether anyone else was involved in the incident. If necessary, they will also be arrested.

The police have lodged a suo motu FIR under various sections of the Bharatiya Nyaya Sanhita (BNS), including culpable homicide and attempt to commit culpable homicide.

Kolkata Police have also formed a Special Investigation Team (SIT) to probe the incident.

The SIT will be headed by the deputy commissioner of police (Detective Department) and includes Joysurja Mukherjee, Assistant Commissioner of Police, Inspector Debasis Dutta, Officer-in-Charge of the Homicide Squad, Inspector Hirak Dalapati, who has been appointed the new investigating officer in the case, Inspector Sarfaraz Ahmed of the Anti-Rowdy Squad and Sub-Inspectors Manas Bhattacharya and Kushal Mondal of Taratala Police Station.

The police said they are probing allegations of construction lapses at the site, including claims that tin sheets were used beneath the concrete roofing structure.

Meanwhile, rescue operations are underway at the accident site. The Indian Army, National Disaster Response Force (NDRF), Kolkata Police's Disaster Management Group, state Fire and Emergency services Department, Kolkata Police and Kolkata Municipal Corporation officials are supervising the rescue operations.

Sources said that about three to four workers are still trapped under the collapsed roof.

Special radar has been brought in to locate the trapped workers. Sniffer dogs have been there since Wednesday.

The roof of an under-construction warehouse collapsed at Taratala on Wednesday afternoon. About 40 workers got trapped inside the collapsed roof. Civil defence, Indian Army, NDRF, Fire Brigade, Kolkata Police and KMC personnel conducted rescue operations on a war footing. Hydraulic cranes and gas cutters were deployed to remove parts of the collapsed roof.

According to locals, the roof of the under-construction warehouse suddenly collapsed as several workers were working inside the warehouse. Locals started rescue operations, and later the police, fire brigade, NDRF and Army teams reached the spot.

Chief Minister Suvendu Adhikari visited the accident site on Wednesday and also met the injured workers at SSKM Hospital in the evening.

The Chief Minister said the incident happened due to a faulty building plan of the under-construction warehouse. He also informed that action will be taken against its owners.

The CM further said that work in all under-construction commercial properties in the Kolkata Municipal Corporation (KMC) area will remain suspended till July 31. "In the aftermath of today's incident, I have given instructions to the KMC to suspend work in all under-construction commercial properties till July 31. We will conduct an audit of their building plan, site plan and on-the-spot inspection. Those whose papers will be in place can resume work from August 1," said CM Adhikari.

/IANS