A portion of an old two-storeyed building in the northern part of the city's Ahiritola Lane collapsed on Wednesday morning in which one person is feared trapped under the rubbles, police said.

A huge team of disaster management, fire department, police personnel from the local police station are at the spot, an officer of Calcutta Police said.

"So far four persons have been rescued. We are trying to rescue two others still trapped under the rubbles. There is still a child and another person underneath," he had said, before the child was rescued.

The portion of the building at 9 Ahiritola Lane, where two families have been staying, collapsed at around 6.45 am, he said.

"One of the two families managed to get out of the rubbles through a big gap, but another family including a child got trapped under the rubbles. Our men have pulled out four and are trying to rescue others," he said.

Locals rushed to the spot and informed the Jorabagan Police Station who along with personnel of the fire department and disaster management department rushed to the spot, the officer said, adding that those rescued have been taken to a nearby hospital.

"The entire building is in a very bad shape and we have to conduct the rescue operations very cautiously otherwise there are chances of another disaster," he added.