At least one person was killed and 16 injured after an explosion at a chemical park in the western German city of Leverkusen on Tuesday, the site's operator said, with four people still missing.
"We are deeply saddened by this tragic accident and the death of an employee," Chempark operator Currenta said in a statement, adding that "rescue efforts continue at full speed" to find the four remaining workers.
The explosion at the industrial park for chemical companies shook Leverkusen, sending a large black cloud rising into the air.
Germany's Federal Office for Civil Protection and Disaster Assistance classified the explosion as “an extreme threat” and asked residents to stay inside, turn off ventilation systems and keep windows and doors closed, German news agency dpa reported.
Later on Tuesday, however, the Cologne fire department tweeted that measurements of the air's pollution “do not show any kind of abnormality”. They said the smoke had gone down but that they would continue to measure the air for toxins.
City officials announced almost four hours after the explosion that the fire had been extinguished but that rescue crews were still searching for the missing.
Currenta, the company operating the chemical park, said the explosion happened at 9:40 am at the storage tanks of their waste management centre and then developed into a fire.
“Sirens were operated to warn residents and warning alerts were sent,” Currenta said in the statement.
Police in nearby Cologne said a large number of officers, firefighters, helicopters and ambulances from across the region had been deployed to the scene. They asked all residents to stay inside and warned people from outside of Leverkusen to avoid the region.
They also shut down several nearby major highways.
Daily Koelner Stadt-Anzeiger reported that the smoke cloud was moving in a northwestern direction toward the towns of Burscheid and Leichlingen.
Leverkusen is home to Bayer, one of Germany's biggest chemical companies. It has about 163,000 residents and borders Cologne, which is Germany's fourth biggest city and has around 1 million inhabitants. Many residents work at Bayer, which is one of the biggest employers in the region.
The chemical park is located very close to the banks of the Rhine river.
Currenta has three facilities in the region. More than 70 different companies are based at the locations in Leverkusen, Dormagen and Krefeld-Uerdingen