Kolkata | At least four workers were killed and three injured after the chimney of a brick kiln collapsed on them in West Bengal's North 24 Parganas district, police said.

The incident happened at Dhaltitah village in Basirhat on Wednesday evening while attempting to restart the brick kiln which was closed for a year, they said.

"Four people are confirmed dead and three have been admitted to hospital," a Barishat police officer said on Thursday.

"Two persons died while undergoing treatment at a nearby hospital, while two bodies were found from under the debris. All of them were workers of the brick kiln," a police officer said.

"Two are under treatment at Basirhat Hospital, while the third individual, who is in critical condition, has been transferred to RG Kar Hospital in Kolkata," the officer added.

Among those killed, two were from Faizabad in UP -- Jethuram and Rakesh Kumar. Another deceased was identified as Hafizul Mondal, a local. The fourth person was yet to be identified, he said.

The cause of the chimney collapse is yet to be ascertained, he said, adding that it will be investigated.