An emergency alert has been issued by authorities in the north German town of Bad Fallingbostel, after a chemical leak at a factory run by US food giant Kraft.
Employees accidentally poured acid into a tank containing sodium hydroxide solution on Monday, causing a chemical reaction. This created nitrous gases that are considered dangerous if they come into contact with the human body.
More than 1,400 people have been evacuated from the area. Kraft says nobody has been injured.
Hundreds of fire fighters are working to cool the container and avert an explosion.