Two people have died after a gunman opened fire on a bus carrying American soldiers at Frankfurt Airport, police say.
The driver of the bus and a US soldier were reportedly killed, while two others were seriously injured.
A 21-year-old suspect from Kosovo is said to have been arrested after the shooting in front of Terminal 2 at Europe's second-biggest airport.
Police have told German media it is not clear if it was a terrorist attack.
Police spokesman Jurgen Linker told Germany's Die Welt newspaper that the incident seemed to have taken place inside the bus.
US Army Europe has not yet issued a comment, but said it was looking into the incident.
The BBC's Stephen Evans in Berlin says the airport is not far from Ramstein Air Base, the US Air Force's headquarters in Europe.
Four Islamists were convicted in March last year in Germany for plotting to bomb targets including Ramstein Air Base.
Last month the German parliament extended by one year the military mission in Afghanistan.
Germany has 4,860 troops there, despite domestic polls suggesting the mission's unpopularity.