A German air force Eurofighter and a civilian Learjet carrying two people collided in mid-air in Germany, crashing the Learjet.
The Learjet crashed in woodland near the town of Olsberg. The fate of the two people on board is not yet known.
The Eurofighter returned safely to its base near Cologne. The incident happened during an exercise with another Eurofighter, German media say.
Die Welt news website says the Learjet was also taking part in the exercise.
Firefighters have found wreckage of the Learjet. Witnesses quoted by the German broadcaster WDR say the Learjet came down just 80m (264ft) from a block of flats.
Olsberg lies in the Ruhr Valley, in North-Rhine Westphalia state.