Eleven people died after a gas leak in Punjab's Ludhiana on Sunday, said officials.?

The gas leak happened in Giaspura area in Punjab's Ludhiana district. The source of the leakage and the type of the gas are yet to be ascertained, they added.?However, Ludhiana Deputy Commissioner Surabhi Malik said it was likely that ?some chemical reacted with methane in manholes.

"We are going to collect samples from manholes. It is quite likely that some chemical reacted with methane in manholes," she said. Those who died in the incident did not show any symptoms of respiratory problems, she added.

"It is likely that the deaths were caused by a neurotoxin," Malik added.

Officials further said that four more people are undergoing treatment in a hospital after falling sick.

Police have sealed the area while a fire brigade and an ambulance have been deployed there. A 50-member team of the National Disaster Response Force (NDRF) has also reached the site.

Police said the deceased comprise five females and six males. Two boys aged 10 and 13 are among the 11 who died in the incident.

An NDRF official said it was yet to be found which gas caused the deaths. "We will check it first then we will let you know," the official said in a response to a query.

A district administration official said a team of the NDRF, which has reached here, will ascertain the source and the type of gas. As it was a thickly-populated area, the immediate priority was to evacuate people from the place, the official further said.

Punjab Chief Minister Bhagwant Mann tweeted that the incident is very sad.

"The incident of gas leak of factory in Giaspura area of Ludhiana is very sad. Police, government and NDRF teams are present at the spot. All possible help is being provided. Rest details soon," said Mann in a tweeted in Punjabi, as per Google translation.?

Rajinderpal Kaur Chhina, Aam Aadmi Party (MLA) from Ludhiana South, described the incident as unfortunate. She said it is yet to be ascertained what led to the tragedy.

(With PTI inputs)