BERLIN, Sept. 1 (Xinhua) -- Eight people were injured in a fire that followed an explosion in an oil refinery near southern German city Ingolstadt, local media reported.

The explosion took place early Saturday morning. Approximately 3,000 to 4,000 residents have been evacuated as a precautionary measure due to black smoke, reported local media "Bayerischer Rundfunk" .

Local media, Focus online quoted the police as saying eight employees of the Bayernoil company were injured and three of them were hospitalized, some with serious injuries.

The cause of the detonation is still unclear. There are still several burning places on the site, the flames are not under control, the Focus Online reported.