Some rises over the area of a Bayernoil refinery in Vohburg an der Donau near Ingolstadt, southern Germany, Saturday, Sept. 1, 2018 after a fire broke out. (Lino Mirgeler/dpa via AP)

Some rises over the area of a Bayernoil refinery in Vohburg an der Donau near Ingolstadt, southern Germany, Saturday, Sept. 1, 2018 after a fire broke out. (Lino Mirgeler/dpa via AP)

BERLIN (AP) — Nine people have been injured in a blaze at an oil refinery in Bavaria, and another 1,800 people living close by were temporarily evacuated.

Police said the fire spread quickly after a loud detonation was heard early Saturday in the southern German town of Vohburg an der Donau. A huge smoke cloud could be seen miles away.

Residents were evacuated because of possibly toxic fumes. Air tests later showed it was safe for people to return to their homes.

The German news agency dpa reported all nine injured were Bayernoil refinery employees. It said some 400 fire fighters and police were on the ground to help extinguish the fire.

Authorities said the cause of the explosion was not known.