Some 600 people were evacuated from their homes in Frankfurt as bomb disposal experts could remove a World War II-era bomb.
According to media reports, the bomb was defused underwater on Sunday, leading to a loud detonation and a big water fountain.
The 250 kg bomb was detected by divers with the city's fire service during a routine training exercise in Frankfurt's River Main.
Even more than 70 years after World War II, bombs and other munitions are still detected in several parts of Germany.

Thailand school shooting toll rises to nine after death of 12-year-old girl
Three killed in Russian strikes in Kyiv region, official says
Typhoon Dolphin hits Japan's Okinawa, China shuts ports ahead of landfall
Spain to establish border controls against Italy amid migration dispute
Thai teen kills 7 in rampage at home and school before shooting himself
