The attack came as the bus sat outside Terminal 2 at the airport, according to Frankfurt police spokesman Manfred Fuellhardt. The bus driver and a passenger were killed, and one person suffered serious wounds and another light injuries, he said. A source tells Fox News that the shooter yelled "Allah Akbar" when opening fire on the U.S. military personnel. He then dropped his gun at the scene, ran into the terminal and was subdued. U.S. Air Force Europe spokeswoman Maj. Beverly Mock said all four victims were airmen. They were all based at the Lakenheath military base in Britain. A...