Explosion rocks chemicals site in western German city of Leverkusen

An explosion rocked a chemical industry site in the western German city of Leverkusen, operator Chempark said on Twitter, adding the cause of the blast was not yet clear.

"Residents should please go indoors and keep doors and windows closed," it said. Broadcaster WDR had cited witnesses as saying they had heard an explosion and that they saw plumes of smoke at chemicals maker Bayer's site.

Police said on Twitter that is was closing a nearby motorway.