Eight people died, with hundreds of others sick, after a gas leak in southern India.
The leak in the city of Visakhapatnam, in the state of Andhra Pradesh, was located at the LG Polymers factory.
Doctors say "hundreds" of people were taken to the hospital – many complaining of a burning sensation in their eyes and difficulty breathing.
The incident, which occurred at about 3 am local time (21:30 GMT), may have been caused by negligence, officials said.
The leak occurred when the plant was being reopened for the first time since March 24, when India went into confinement to contain the spread of the coronavirus.
The state's Minister of Industries, Goutam Reddy, told BBC Telugu that it appeared that proper procedures and guidelines were not followed when the plant was being reopened.
As the gas spread, residents left the house in a panic. Anguishing images of people who pass out and are unconscious on the streets are being shared on social media.
Some factory workers are believed to have been there when the spill occurred, but officials say they have no information about them.
It is feared that the smoke has spread over a radius of about 3 km (2 miles) and the authorities have evacuated people from the surrounding areas.
A senior district official said initial attempts to control the gas leak were unsuccessful. However, local news agencies reported that the situation is now under control.
Meanwhile, Rajendra Reddy, chief official of the Andhra Pradesh Pollution Control Council, told the BBC that the leaked gas was styrene, which is usually cooled.
"We are trying to understand the long-term impact of the chemical on those who inhaled it during the spill," he said.
Meanwhile, authorities ask people to protect themselves by covering their faces with a wet cloth.
India has a tragic history of gas leaks.
In 1984, a chemical leak at a plant in the central city of Bhopal killed thousands of people, which is recognized as the worst industrial disaster in the world.
More than 35 years later, victims say children are still being born with disabilities because of the effects of the spill.
BBC Telugu report by Satish Balla and Deepthi Bathini
What is styrene and how can exposure affect humans?
- Styrene gas is a colorless or light yellow flammable liquid, used mainly in the production of plastics and polystyrene resins – it is used in the manufacture of plastics and rubbers used in food containers, packaging, synthetic marble, floors, disposable and molded tableware furniture
- Breathing in air contaminated with styrene vapors can cause irritation in the nose and throat, coughing and wheezing and create an accumulation of fluid in the lungs.
- Exposure to larger amounts can result in the appearance of "styrene disease", the signs and symptoms of which include headache, nausea, vomiting, weakness, tiredness, dizziness, confusion and awkward or unstable movement (collectively known as central nervous system depression )
- In some cases, exposure to styrene can also result in irregular heartbeat and even coma
- Several epidemiological studies suggest that there may be an association between exposure to styrene and an increased risk of leukemia and lymphoma, although the evidence is inconclusive
PHE Center for Radiation, Chemical and Environmental Hazards and US Environmental Protection Agency information