Police in northwestern Germany say they have yet to determine what caused a massive explosion that seriously injured one person at a chemical processing company.

Police spokesman Marcus Neumann said Wednesday that investigators had arrived at the site in Ritterhude, near Bremen, but were unable to enter because firefighters were still working to douse the embers.

Neumann said a person who was reported missing turned out to be a 60-year-old company employee who suffered lift-threatening burns when he rushed to the scene of the blast.

The explosion at the Organo Fluid company happened Tuesday at 9 p.m. local time (1900 GMT) and could be heard for miles. About 300 firefighters worked all night to extinguish the intense fire.