A fire broke out at an illegal six-storey plastics market in the Indian city of Calcutta early Wednesday morning, killing at least 19 people, police said.

The blaze, which started before 4 a.m. local time, was likely caused by a short circuit, said West Bengal fire minister Javed Khan. The fire was under control by mid-morning, he said, but toxic gases being released by the blaze were hampering rescue efforts.

A police official, speaking on condition of anonymity because he was not authorized to speak to the media, said at least 19 people had died. He said police were looking for the owner of the building, which was filled with dozens of small shops selling various plastic products.

Another 10 people were hospitalized in critical condition and the death toll was expected to rise, Khan said.

Women mourn the death of a relative who was killed in a fire that broke out at a multi-storey market complex in Calcutta on Wednesday. (Rupak De Chowdhuri/Reuters)

He called the scene of the fire "an illegal, unauthorized market."

However, local residents said the market had been operating in the building for nearly 40 years. They said there was only one entrance to the building, which made rescue efforts difficult.

The building housed several warehouses on its upper floors, where chemicals, paper and plastics were stored.

Police said the victims were porters working in the market, who also slept there at night. Eighteen of the dead were men.

Safety regulations ignored

Mamata Banerjee, the state's top elected official, who visited the site soon after the blaze was brought under control, issued an ultimatum to the building's owners to install fire safety equipment within two months.

Banerjee said the previous government that ruled the state for more than three decades had allowed the building to operate without any permits or safety measures.

She said she has ordered police, fire service and the city administration to file a report on the cause of the blaze and take steps to prevent the recurrence of such fires.

In December 2011, at least 93 people died in a deadly fire in a hospital in Calcutta. Soon after that, Banerjee had promised that her government would crackdown on lax safety procedures in public buildings.

Safety regulations are routinely ignored in India, where fire stairways and evacuation drills are rare. Even if fire extinguishers are present, they are commonly several years old and almost never serviced.