A three-storey under-construction warehouse in the Taratala area of west Kolkata collapsed on Wednesday afternoon, trapping several people underneath the rubble, police said.A Kolkata Police official said 10 people had so far been rescued and taken to hospital.”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.Massive chunks of iron beams and concrete crumbled during the construction, where several workers were engaged. Eyewitnesses at the site said they heard trapped victims crying for help from beneath the debris.”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.According to a fire department official, the roof of the warehouse collapsed during casting work. He also alleged that substandard materials were being used in the construction of the warehouse.Personnel of the Kolkata Police, Disaster Management Group, civil defence, and fire and emergency services teams were seen carrying out rescue operations at the site on a war footing.Army officials were also seen aiding rescue operations, while cranes and heavy equipment lifting machinery were deployed at the site to remove the collapsed iron beams.Gas cutters were being used to cut through the iron and concrete, and rescue workers were trying to reach the trapped victims by means of 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.Control room numbers — 1070, 86979 81070, 033-2214 3526/2253 5185 — of the Disaster Management Group were opened at the state secretariat in the wake of the incident.Some locals alleged that large-scale illegal construction activities had been carried out 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 have also rushed to the spot. BJP leader Rakesh Singh arrived at the spot earlier.