Jammed gun saves lives in Frankfurt shooting

The alleged gunman, they add, has confessed, saying he wanted to kill Americans "as revenge for the American mission in Afghanistan", though there is no evidence he was part of any terrorist group.

Washington has released details of the two airmen killed in Wednesday's attack, which left two others wounded.

Officials waited to reveal their identities until their closest relatives had been notified.

The dead men were named as Senior Airman Nicholas Alden, 25, of Williamston, South Carolina, and Airman First Class Zachary Cuddeback, 21, of Stanardsville, Virginia.

Dramatic details of the attack were given to reporters by federal prosecutor Rainer Griesbaum on Friday. Among other things, it emerged that one of the gunman's would-be victims had given chase and caught him after the attack.

The suspect has been named as Arid Uka, 21, an ethnic Kosovo Albanian said to have been born in Germany.

Uka has been charged with two counts of murder and three counts of attempted murder.

Uka said when he saw the busload of 15 airmen parked outside the airport's Terminal 2, he approached an airman outside and, under the pretext of asking for a cigarette, asked if the servicemen were on their way to Afghanistan. When he said yes, he shot the serviceman from behind in the head.

Uka then allegedly stormed on to the bus, yelling "Allahu Akbar!" (Arabic for "God is great!") and shot the driver in the head, killing him as well.

He then allegedly shot a 25-year-old airman who was sitting on the bus twice, and then turned his gun on another airman, 21, and fired once, injuring him too.

He also attempted to shoot another 22-year-old but his pistol jammed and no shots came out.

Unable to fire again, Uka allegedly fled from the bus but the would-be final victim gave chase and caught up with him in the terminal at the same time as two German police officers, and apprehended him.

German authorities believe that Uka became an Islamic radical recently and was not part of a wider network.