Two people were shot and killed Wednesday in an incident involving a U.S. military bus at Frankfurt Airport in Germany, a police spokesman said.
Another person is severely wounded, Juergen Linker told CNN, and one person is in custody.
A U.S. military official said initial reports were that two people had been killed, including the driver of the bus.
It is not clear if the driver was German or American, or military or civilian.
Two others are wounded, said the source, who is not authorized to speak publicly about the incident.
The troops killed and injured are U.S. Air Force airmen from Lakenheath base in the United Kingdom, the U.S. official said, emphasizing that the information was only preliminary.
They were security forces on their way to a deployment, the source added without saying where they were heading.
They were flying commercial, according to the source.
It's believed the German police have a young Kosovo national in custody, the U.S. official said.
The U.S. military base at Ramstein, Germany, regularly runs shuttles to Frankfurt for commercial flights.