At least two people are feared dead after an under-construction building collapsed in Kolkata's Taratala area on Wednesday afternoon, trapping several workers beneath the debris, according to reports.

The incident occurred at around 1.30pm near Brace Bridge railway station at a godown belonging to Octavius Tea & Industries.

Local residents said between 25 and 30 people were inside the structure when it gave way. While reports suggested that at least two people may have been killed, there was no official confirmation of the death toll at the time of writing.

A Kolkata Police official said 10 people have so far been rescued, reported PTI.

Residents and workers in the area said the three-storey iron-and-cement shed had been under construction for nearly a year and was undergoing renovation work. The structure reportedly collapsed from the third floor to the ground, bringing down multiple levels and trapping workers under the rubble.

Some locals alleged that large-scale illegal construction activities had been carried out in the area for some time, reported PTI.

"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 told PTI.

According to a fire department official, the roof of the three-storey under-construction warehouse collapsed during casting work. He also alleged that substandard materials were being used in the construction of the warehouse.

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.

Police from Taratala police station, along with personnel from the fire department, rushed to the scene and launched rescue operations. Bulldozers and steel-cutting equipment were brought in to clear the debris and reach those feared trapped underneath.

Several injured workers were taken to SSKM hospital for treatment, while rescue teams continued searching for others believed to be trapped in the wreckage.

Authorities are yet to issue an official statement on the cause of the collapse or confirm the exact number of casualties and injuries.

A Kolkata Police official said that four people have so far been rescued.

"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.

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. 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, 8697981070, 033-22143526/22535185 -- of the Disaster Management Group have opened at the state secretariat for the incident.