Fearing that there may be toxic gases, a chemical complex in Leverkusen exploded and declared an “extreme threat.”

After an explosion in an industrial park in the western German city of Leverkusen, five people were missing and several others were injured.

Tuesday’s incident sent heavy smoke billowing into the sky and prompted the authorities to require nearby residents to stay at home while issuing warnings of “extreme threats”.

The operator Currenta stated that the explosion occurred at 9:40 am local time (07:40 GMT) and caused a fire in the fuel depot of Chempark, an industrial park of chemical companies including Bayer and LANXESS.

It added that several staff were injured and at least two were seriously injured.

The company said that it is not yet clear what caused the explosion and subsequent fire.

The authorities stated that a large number of police, firefighters, helicopters and ambulances have been deployed to the scene.

At the same time, the emergency alert of the German Civil Defense Agency’s mobile app listed the explosion as an “extreme threat” and required local residents to stay indoors and close doors and windows.

Currenta said that people in nearby houses should also turn off the air-conditioning system and measure possible toxic gases in the air around the site.

Several nearby highways have been closed, and the police said that drivers should avoid the area by detour.

According to its website, there are more than 30 companies at the site, which is very close to the banks of the Rhine.

Bayer and LANXESS sold Chempark operator Currenta to Macquarie Infrastructure and Real Assets for an enterprise value of 3.5 billion euros (US$4.12 billion) in 2019.