A large fire broke out at a petrochemicals plant in Russia's Tatarstan region on Tuesday, killing at least three people, including a firefighter, and injuring dozens.
Sibur, the company that owns the sprawling Nizhnekamskneftekhim complex, said two employees had been killed in the accident, with 68 injured. Twenty-one people remained hospitalized, three in serious condition.
The branch of Russia's Emergencies Ministry in Tatarstan said one firefighter died from injuries sustained from a nearby explosion. Three others were injured.
Sibur said a gas mixture had exploded following a loss of pressure at a facility producing synthetic rubber and plastics. It said it was not clear what had caused the gas to ignite.
Sibur CEO Mikhail Karasalov said in a statement that production at the plant would be reduced by about 6% of its annual output of 180,000 metric tons "but the focus at this time is on people, not the number of tons."
Firefighters had contained the blaze and there was no risk of it spreading, the company said, adding specialists were checking air quality and had not detected any threats to the environment or local residents.
The Emergencies Ministry, in a statement quoted by news agencies, said an aircraft had been dispatched from Moscow to Nizhnekamsk, about 1,000 km to the east to bring the injured to the capital for treatment.
Russia's aviation regulator briefly imposed restrictions at the Nizhnekamsk airport.
Radmir Belyaev, the local mayor, said in a statement that windows had been blown out in several apartment blocks.
Unconfirmed images on social media showed a large plume of smoke billowing into the sky from the complex.
Unconfirmed images on social media showed a large plume of smoke billowing into the sky from the complex.

Putin says US-Russia contacts beneficial as talks begin with Witkoff and Kushner
Chinese national rescued from Nepal tunnel 10 days after flash flood
US envoys Witkoff, Kushner arrive in Moscow for talks on peace in Ukraine
One dead, 11 people missing after mudslide in China's Jiangxi province
Philippine VP Duterte posts bail after arrest order for alleged grave threats
Lindsay Clancy trial over killing her children ends in mistrial
Israel says it strikes southern Lebanon after Hezbollah drone launch
Sydney sweats in spring hot spell, faces 'extreme' bushfire risk
