LEVERKUSEN — More than a dozen people have been injured and five more were missing Tuesday after an explosion at a chemical park in the German city of Leverkusen. Sixteen people were injured because of the blast, including four "seriously," the municipality said in a statement released after midday. "Five people are missing," it added. The explosion took place at around 9.30 a.m. CET at a waste incineration plant at Chempark in Leverkusen, a city in the western North Rhine-Westphalia region. The cause of the explosion remains unclear. Germany’s Federal Office for Civil Protection and Disaster Assistance classified the explosion as “an extreme threat”, German news agency DPA reported. The municipality said that a tank of solvents was on fire at 12:20 p.m. CET, explaining that "the extinguishing work had to wait until a power line was disconnected from the grid." "That has now happened. The extinguishing work begins," it added. A fire brigade from Cologne, about 20 km south, has been deployed to assist local emergency services, the municipality said. Authorities have called for people to keep windows and doors closed and to keep clear of the Buerrig area where the Chempark is located. Several highways have been partially closed. Operators of the Chempark said on Twitter that pollution detection vans had been deployed. Leverkusen is home to Bayer, one of Germany"s biggest chemical companies. — Euronews