An old aircraft bomb has exploded at a bridge near Munich's busy main train station, injuring three people, police said on Twitter.
One of the three was seriously injured, the Munich fire brigade said.
The explosion happened during drilling work on a construction site, police said. The danger area had been cordoned off.
"There is no danger outside this area," police said.
Due to the explosion, rail travel to and from the main train station has been suspended, according to rail operator Deutsche Bahn. It was not clear when the rail traffic could resume.
More than 2,000 tonnes of live bombs and munitions are discovered each year in Germany, more than 70 years after the end of World War II.
British and Us warplanes pummelled the country with 1.5 million tonnes of bombs that killed 600,000 people.
Officials estimate that 15% of the bombs failed to explode, some burrowing six meters.