MUMBAI (Reuters) - A blaze in a building under construction in a suburb of the Indian city of Mumbai killed at least six people, most of them laborers, and injured nearly a dozen, fire and police officials said on Thursday.

The cause of the fire, which broke out late on Wednesday, was being investigated, a fire service officer said. It is likely to compound concern about safety in the financial hub after an old building collapsed last week killing 34 people.

Laborers working on the building were living on the ground floor, some with families, and cooking gas canisters were believed to have exploded in the fire, fuelling its spread.

“Though the fire was brought under control immediately, all injuries and deaths occurred before the arrival of the fire brigade,” said P.S. Rahangdale, chief officer at the Mumbai Fire Brigade.

Eleven people were injured, eight of them critically, he said.

Mumbai has endured torrential monsoon rain and serious flooding over recent weeks. The building collapsed last week in a congested neighborhood of the old city after two days of intense downpours.