Portions of the first and second-floor balconies of a three-storey building on Rashbehari Avenue, near the Keoratola crematorium, collapsed on Friday morning, injuring two persons.

The injured were sitting at a tea stall on the pavement under the building.

Police said one of the two persons received relatively serious injuries.

Tapan Biswas, 65, a resident of 108 Tollygunge Road, was taken to MR Bangur Hospital where he was treated. He was discharged after a few hours.

According to eyewitnesses, like any other day, several people were sitting and chatting at the tea stall on the pavement under the old dilapidated building when a chunk of concrete fell from the top and landed on the head of one of them.

“The elderly person (later identified as Tapan Biswas) was bleeding from his head. He was rushed to the hospital,” said a shopkeeper in the neighbourhood.

As soon as the incident was reported, members of the disaster management group and Kolkata Municipal Corporation (KMC) officials reached the spot and started demolishing the balconies.

A KMC official said it was a condemned building and residents had been warned against staying inside.

However, according to people in the neighbourhood, one or two families still lived in a portion of the three-storey building.

“The structure was declared a dangerous building. The owner was served notice to repair the building several times. Several portions of the building collapsed earlier,” said Mala Roy, the councillor of Ward 88 of the Kolkata Municipal Corporation. She is also the MP from Kolkata South.

A stretch of the flank of Rashbehari Avenue was closed to traffic for the demolition work that went on till late in the afternoon on Friday.

Police said traffic was regulated through the remaining portion of the flank.

The night-long rains in the city that soaked the old building may also have caused a portion to cave in, residents of the area said.

“This building has been in a precarious state for several years now. We fear it will collapse part by part as it did today and crash on our cars or people standing underneath. The monsoon makes it more vulnerable” said a resident of the locality.

According to the civic records, several hundred old dilapidated buildings, which are in a dangerous state, exist in the city. They have been served notices.