The management of the firm whose chemical plant in Vishakhapatnam suffered a deadly gas leak on Thursday morning should be held responsible for the accident, the state industry minister said.

Several people were killed after the leak occurred at around 2.30 am, and many were rushed to hospitals with complaints of headaches, vomiting and breathing difficulties. (Get live updates here.)

The firm operating the plant, LG Chemical Ltd., "should have been extra careful...especially since it was a prolonged lockdown", said Mekapati Goutham Reddy, Andhra Pradesh's Minister for Industries, Commerce, and Information Technology.

The government had asked the firm to do a thorough check and a self-certification, Reddy told India Today TV.

Authorities will take strict action after assessing the extent of its failure to manage the facility, he said.

Meanwhile, Prime Minister Narendra Modi said the central government was monitoring the situation closely.

He spoke to officials from the Home Ministry and the National Disaster Management Authority, as well as Chief Minister YS Jagan Mohan Reddy.