FRANKFURT, Germany, March 2 (UPI) -- Two U.S. service members were shot and killed Wednesday on a military bus at Frankfurt Airport in Germany, and two others were wounded, officials said.
Preliminary information was that the two military personnel killed were U.S. Air Force airmen from Lakenheath base in the United Kingdom, CNN reported.
"I'm saddened and I am outraged by this attack that took the lives of two Americans and wounded two others," U.S. President Obama said at the White House. "I think the American people are united in expressing our gratitude for the service of those who were lost. …
"We will spare no effort in learning how this outrageous act took place and in working with German authorities to ensure that all of the perpetrators are brought to justice," Obama said.
The airmen were part of a security force on their way to a deployment, a military source told CNN, but it was not revealed what their exact destination was.
The gunman, believed to be from Kosovo, opened fire on the bus in front of the airport's Terminal 2, Britain's The Guardian reported.
Police said it appeared an argument had broken out on board the bus before the suspect opened fire.
The alleged gunman fled but was arrested inside the terminal shortly afterward, the report said.
Kosovo's interior minister, Bajram Rexhepi, said German police had identified the suspect as 21-year-old Arif Uka, from the northern town of Mitrovica, The Guardian reported.
"This is a devastating and a tragic event," Rexhepi said. "We are trying to find out was this something that was organized or what was the nature of the attack."
The forces heading for deployment were flying commercial, not on a military plane, and the U.S. military base at Ramstein in Germany regularly runs shuttle buses to Frankfurt Airport for personnel taking commercial flights, officials said.
