Four injured as old bomb explodes near train station in German city of Munich - CNN

The explosion was caused by an old aircraft bomb, Munich police press officer Carolin Schrott told CNN.

"There is no danger outside the immediate area," police said.

No further information was available on the type of bomb involved but munitions dating back to World War II are not uncommon finds in Germany.

More than 70 years after the end of the war, roughly 2,000 tons of live bombs and munitions are still discovered in the country each year, Reuters reported.

According to official estimates, some 15% of the World War II bombs did not explode, and in some cases are buried six meters (20 feet) below ground.