Two people were killed and two others were missing after an explosion on Monday (Oct 17) at a chemical plant at BASF's headquarters in western Germany, the firm said, advising local residents to stay indoors.
Six other people were seriously injured in the blast, the global chemicals giant said on its Twitter account.
The explosion occurred around 11.30am (5.30pm Singapore time) and triggered a huge fire during work on a pipeline that transports raw materials.
Peter Friedrich, the fire brigade chief in the city of Ludwigshafen where the plant is located, said firefighters hoped to put out the blaze on Monday night despite "uncertainty over the nature of the gases".
A large fire and a huge column of grey smoke rose into the sky from the site, a vast industrial complex with a harbour on the Rhine river.
Hours after the explosion, firefighters including a fireboat crew were still trying to extinguish the flames, an AFP reporter said.
"We have not been able to establish any danger to the population," BASF executive Uwe Liebelt told reporters earlier in the day, after residents in Ludwigshafen and nearby Mannheim were told to remain inside and shut doors and windows until the fire was out.
Local authorities had also asked nurseries and schools to keep children indoors, but no evacuations were ordered.
"Emergency services from the whole region are on the scene to prevent the fire spreading to other parts of the plant," city authorities said.
BASF said it was still investigating the precise cause of the blast.