A three-storey warehouse under construction collapsed in the Taratala area of west Kolkata on Wednesday afternoon, trapping dozens of people beneath the rubble, police said.
Ten people have been rescued and taken to a nearby hospital, according to a Kolkata Police official.
"The roof of the warehouse located on the Transport Depot Road near Brace Bridge in the Taratala area collapsed around noon. Our officers have reached the spot. Some people were working at the site at the time of the incident. We fear that quite a few people may be trapped under the debris," the officer said.
Large sections of iron beams and concrete crashed down during construction work, when several labourers were at the site.
Witnesses said they could hear people trapped beneath the debris calling for help.
"Construction activities were taking place on the ground floor while the RCC structure for the first and second floors had been completed. The entire structure has come crashing down," an eyewitness said.
A fire department official said the roof collapsed during casting work and alleged that substandard materials had been used in the construction of the warehouse.
Rescue teams from the Kolkata Police, Disaster Management Group, civil defence and fire and emergency services were deployed to the site.
Army personnel were also assisting in the operation, while cranes and heavy lifting equipment were being used to remove collapsed iron beams and concrete.
Gas cutters were being used to cut through the debris, while rescuers attempted to reach those trapped through vertical drilling.
"We are following the cries for help coming from under the debris. At the same time, we are assuring the trapped people that they will be rescued soon," a member of the Kolkata Police disaster management group said.
The state government opened Disaster Management Group control rooms at the state secretariat following the collapse.
Some local residents alleged that illegal construction activities had been taking place in the area for some time.
"We will definitely look into the causes of the accident and whether there were any irregularities. But right now, the priority is to rescue as many victims as possible," Minister Indranil Khan said.
Urban Development Minister Agnimitra Paul and Kolkata Municipal Commissioner Smita Pandey also visited the site.
This is a developing story.
(With inputs from PTI)
