Two people have been killed, after a gunman, fired at U.S. Air Force personnel, on a bus, outside Frankfurt airport.

Two others were also wounded, in the attack outside the airport's terminal 2 on Wednesday, before the gunman was apprehended. The bus driver, and a passenger were killed and there were unconfirmed reports that the two victims were members of the US military.

German police have identified the 21-year-old suspect as Arif Uka, from Kosovo. There were no details of his motives for the attack. President Barack Obama said that he was "saddened and outraged" by the incident.