At least one person died in an explosion in a German industrial park in Leverkusen city on Tuesday afternoon.
Sixteen other people were injured, and four others remain missing during the fatal incident.
A fierce blaze and a pall of smoke were seen over the western city of Leverkusen.
“This is a tragic moment for the city of Leverkusen,” said Uwe Richrath, mayor of the city.
The head of the industrial park, Lars Friedrich, said in a statement: “We are deeply saddened by this tragic accident and the death of an employee.
“Our special condolences go out particularly to the relatives, but also to the colleagues who have worked with him.”
Chempark operator Current said multiple staff were hurt, with one person facing possible life-threatening injuries. It said it hopes those who remain missing will be found alive.
It is not yet clear what caused the explosion, Current added.
The blast happened at around 9:40 a.m. (0740 GMT) “for still unknown reasons,” Chempark operator Current said in a statement, adding that a fire that had broken out had been extinguished.
However, residents have been asked to remain inside their homes, keeping doors and windows closed.
This came as the country had witnessed deadly floods over the past few days.
More than 180 people died in Western Europe due to the floods.
While about 157 German people died after the flood, only 31 from Belgium died. And about 163 people are still missing.
Other countries like France, Netherlands, Austria and Switzerland have also been affected by the worst flood Europe has been in living memory.
Experts say such disasters will become more severe and frequent as the planet heats up.