Firefighters prevented a second explosion at a chemical plant in the western German city of Leverkusen after the first one happened in a solvent container.

This was announced by the Minister of the Interior of the state of North Rhine-Westphalia Herbert Royle, quoted by DPA.

He said the other tank contained 100,000 liters of flammable toxic waste. 300 firefighters are working on the scene, he said.

The explosion, which occurred at 9.40 am local time yesterday in an industrial area for the disposal of chemical waste materials, killed two and injured 31 people, and four are still unaccounted.

The blast sent pillars of smoke into the sky.

Police urged residents in the area not to leave their homes, keeping the doors and windows of their homes tightly closed.

It is still impossible to start an investigation into the cause of the industrial accident.