Gas leaked from a chemical plant in Visakhapatnam in the early hours of Thursday and quickly spread to villages in a five-kilometre radius, killing at least 11 people and impacting about 1,000, many collapsing to the ground as they tried to escape the toxic vapours.
Hours after the styrene gas leak around 2.30 am from the multinational L G Polymers Plant at R R Venkatapuram village near Vizag, scores of people could be seen lying unconscious on sidewalks, near ditches and on the road, raising fears of a major industrial disaster.
Among the dead were two children, aged six and nine, a first year medical student and two people who fell into a well while fleeing the vapours from the plant, getting ready to reopen after the lockdown.
Cries for help broke the silence of the night and many people fell unconscious in their sleep, a villager said.
As rescue officers and police personnel rushed to take people to hospital and revive them, many people could be seen gasping for breath as they staggered their way to safety, dazed and disoriented. Some tried to walk but fell to the ground in a faint.
The death toll from the accident could go up with at least 20 people on ventilator support. Besides, 246 people with health complications are undergoing treatment at Visakhapatnam's King George Hospital, police said.
About 800 people in ground zero, R R Venkatapuram village in Gopalapatnam, were evacuated and most needed only first aid.
"Initially I thought that it was an LPG cylinder leak. When we came out we realised it is a leakage from the L G Polymers factory near our village," said G Vinay, who lost his uncle in the tragedy.
Narendra said he saw many people slowly losing their strength and falling to a heap, unconscious.
"We were fast asleep. Around 2.30 am I woke up as my skin was itching. I opened my eyes but felt a burning sensation. I sensed some danger and woke up my family," he said.
A preliminary report by the Factories Department indicated the leak was caused by a technical glitch in the refrigeration unit attached to the two styrene tanks, district officials said.
"There was a thick fog. Only around 9.30 am that we could understand what exactly it was after the fog over the area cleared," District Collector V Vinay Chand said.
As much as 1,800 tonnes of styrene is said to have been in the storage tank when the leakage happened.
Styrene gas, used to make polystyrene plastics, fibreglass, rubber, and latex, affects the central nervous system, throat, skin, eyes and some other parts of the body.
Taking stock of the situation, Prime Minister Narendra Modi said he had spoken to officials of the ministry of home affairs and the National Disaster Management Authority.
"I pray for everyone's safety and well-being in Visakhapatnam," Modi said in a tweet.
President Ram Nath Kovind and Vice President M Venkaiah Naidu also expressed their distress and condoled the loss of lives.
Addressing a joint press conference in Delhi in the afternoon National Disaster Response Force and NDMA officials said 11 people died and 1,000 were exposed ,to the gas.
NDRF Director General S N Pradhan said NDRF personnel would be at the spot till it is totally plugged.
Andhra Pradesh Chief Minister Y S Jaganmohan Reddy has ordered a probe into the matter, state Director General of Police D Gautam Sawang said.
"How the gas leaked and why the neutraliser at the plant did not prove effective in containing the leak will all be investigated. Styrene, though, is not a poisonous gas and can be fatal only if inhaled in excess quantity," Sawang said.
Though the source of the leak was contained in the morning, the effects were seen for many hours after.
Daybreak revealed the full magnitude of the tragedy.
Hundreds of villagers, most of them children, suffered from irritation in their eyes, breathlessness, nausea and rashes.
Everyone helped as they could, some offering first aid, others water, dabbing and wiping people's faces. Those affected were rushed to hospitals in autos and two-wheelers while government workers and others tried to assist in whatever way possible.
In disturbing visuals from the spot that flashed across news and social media, a man, his eyes rolling back, was being put into an ambulance. Another just slumped to the ground near a scooter, stunned and looking blank. Two children hugged each other as a rescue worker tried to revive a woman, possibly their mother.
Cattle and birds were also knocked unconscious by the gas leak.
The grim scenes recalled the Bhopal gas leak, the world's worst industrial disaster in which more than 3,000 people were killed and lakhs affected when methyl isocyanate gas leaked out from a Union Carbide plant on the intervening night of December 2-3, 1984.
State Industries Minister Mekapati Goutham Reddy said the LG Polymers unit was supposed to reopen post-lockdown on Thursday.
He said the state government is airlifting 500 kg of inhibitors from Gujarat to neutralise the chemicals.
The 20-odd workers in the plant were well-versed with safety protocol and took appropriate steps and therefore did not suffer, sources said.
The Greater Visakhapatnam Municipal Corporation put out an advisory on Twitter, asking people to wear a wet cloth or mask, eat banana and jaggery and drink milk to neutralise the effects of the gas.
South Korean firm LG Chem, which operates the plant, said it is cooperating with Indian authorities to help residents and employees.
"We are investigating the extent of damage and the exact cause of the leak and deaths," it added.
Stating that plant operations were suspended because of the coronavirus lockdown, the firm said none of its employees died in the accident.
The leak was noticed by company staff who were reportedly inspecting machines to restart the factory and raised an alarm.
Political leaders, including Union Home Minister Amit Shah, Bharatiya Janata Party president J P Nadda, Congress leader Rahul Gandhi and Telangana Chief Minister K Chandrashekar expressed their shock at the incident.
The accident impacted the movement of trains from Visakhapatnam, including at least nine Shramik Special Trains taking migrants to various places. Staff at the SCMN station also experienced burning in the eyes and suffocation.
Highlighting the importance of safety as industrial units begin to open after an extended lockdown, which began on March 25, seven workers fell ill after inhaling a poisonous gas in a paper mill in Chhattisgarh's Raigarh district.
The Shakti Paper Mill had remained shut since the lockdown and cleaning work was underway to resume operations, an official said.
Union Chemicals and Fertilisers Minister D V Sadananda Gowda on Thursday urged all public and private chemical makers to exercise caution and care while reopening their plants.