Germany Suspects 'Islamist Motivation' behind Attack on U.S. Airmen

German federal prosecutors said Thursday they suspected an "Islamist motivation" was behind the fatal shooting of two U.S. airmen on a military bus at Frankfurt airport.

"In view of the circumstances, there is a suspicion that this was an act with Islamist motivation," prosecutors said, as police questioned a 21-year-old suspect of Kosovan origin arrested after Wednesday's attack.

The man, named in media reports as Arid U., also left two U.S. airmen seriously injured as he opened fire in the mid afternoon attack at one of Europe's busiest airports. He was arrested in the terminal building.

Germany's interior minister said he saw no need at present to boost security measures after the attack.

"Investigations have produced so far no leads that would necessitate ordering a boost of police presence across the whole country," Hans-Peter Friedrich told.

German media reports have reported growing evidence that the alleged gunman was an extremist.

Federal prosecutors, who in Germany are responsible for "terrorism" cases and who took over the investigation on Thursday, said the suspect would be brought before a magistrate later on Thursday.

A "saddened and outraged" U.S. President Barack Obama said Washington would "spare no effort in learning how this outrageous act took place," while Chancellor Angela Merkel promised Germany would "do all it can."