At least four workers were killed when a fire engulfed a hosiery factory in Ludhiana city in Punjab on Wednesday morning. The workers died of asphyxiation as they were unable to find the exit, The Tribune reported.

The factory is located in a three-storey building in Kalyan Nagar area. The fire broke out at 4.25 am, and took almost four hours to be put out.

Ludhiana Commissioner of Police Sukhchain Singh Gill claimed that gross negligence on the part of the factory owner, such as keeping the exit doors locked, was responsible for the deaths. He said the owner, who has not been identified, had been detained.