WASHINGTON -- An armed security guard fired at least 10 shots at another guard during an argument outside a busy entrance to Walter Reed Army Medical Center early Wednesday, police said. No one was hurt. "This was rush hour on a busy thoroughfare. There were cars and pedestrians in the line of fire," said police Cmdr. Hilton Burton. At least two parked cars across the street were hit. The guard who was fired upon ran to a nearby house to call police. The other guard, Dwan Thigpen, 34, of Fort Washington, Md., was arrested and charged with assault with intent...