At least one person is believed to have been killed after two helicopters collided and crashed in Berlin on Wednesday.
The crash happened near the city's Olympic Stadium during a police exercise, according to the Bild newpaper. More than 400 police personnel were conducting an operation at the stadium to deal with football violence.
The two helicopters collided as they approached for landing during an exercise of the federal police, AP reported.
Federal Police spokesman Frank Brochert confirmed that there had been "an incident during an exercise" and that emergency crews were at the scene.
An eyewitness, Johannes Malinowski, told n-tv television: "there was a big bang and someone shouted, 'everybody on the ground'.
"And then we looked up and there was blood on the ground."
Pictures showed police and emergency services on the wreck of one of the aircraft, seemingly attending to someone inside.