At least three workers were burnt to death when a huge fire broke out in an industrial unit in Karachi's Baldia Town, officials and witnesses said on Wednesday.

One of the victims reportedly died while trying to save other trapped workers.

The factory management blamed delayed response of the fire brigade for the deaths, while the Karachi Metropolitan Corporation (KMC) fire chief and police believed 'criminal negligence' of the factory owners was behind was the tragedy as the unit was constructed like a "prison" and without provision of emergency exits purportedly to prevent thefts.

Workers at the factory of Al-Makkah fabrics told reporters the blaze that erupted on the ground floor rapidly engulfed three other storeys of the building. One employee claimed the fire occurred at 11:00pm on Tuesday and the owner informed the fire brigade at 11:30pm but fire tenders reached the site at 1:00am on Wednesday.

The factory owner, Imran, told media the loss of lives could have been prevented if the fire tenders had reached on time. He admitted that the building was enclosed with high walls to prevent theft.

However, the chief fire officer, Mobin Ahmed, denied charges of a delayed response and said there was no emergency exit in the building.

Medina Colony Station House Officer Saleem Rind corroborated the view of the firemen. The officer told Dawn the ground-plus-three storeys factory was spread over 600 square yards and looked like "a prison" with huge walls and only one gate. He said even the windows were covered with grills so thick "even a sparrow could not enter them".

Rind said even if the grills had been broken, the firemen couldn’t have rescued the trapped workers. He said legal proceedings will be initiated against the factory owners over criminal negligence and loss of human lives.

According to the officer, relatives took away two of the bodies for burial in Rahim Yar Khan while the third worker was laid to rest in the city's Saeedabad locality.

Police were waiting for the deceased's relatives to lodge a first information report (FIR).

The deceased were identified as Ali Sher Hyderi, Mohammed Kazim, 21, and Fayaz, 20.

Hyderi’s father, Saleem, told reporters that his son had managed to escape from the factory after the fire started but after hearing the cries for help of his co-workers, he returned and died while trying to rescue two other workers.

A fire brigade officer said the blaze was brought under control at 8:00am on Wednesday by five fire tenders. One fireman was also injured during the rescue operation, he added.

Police said threads had been stored in the factory which worked like chemicals to spread the fire rapidly.

The cause of the inferno and the resulting estimated loss could not be ascertained immediately.

Pakistan has a dismal industrial safety record, with deadly incidents taking place regularly.

In 2012, more than 260 workers were burnt alive in the multi-storey building of the Ali Enterprises garment factory in Baldia Town in what was the worst industrial disaster in the country’s history.

Last month, 52 modern fire tenders arranged by the federal government had arrived in Karachi in an effort to boost the city's fire emergency system. Sindh Governor Imran Ismail had said the fire department would be responsible for the fire engines and they would come under the ownership of the KMC.