A passenger on a downtown Metro-bus was fatally shot last night, apparently during an argument with another passenger. Police said a suspect was arrested within minutes of the 7 p.m. incident and charged with homicide.

The victim was identified as John E. Ross, 33, of 1369 Spring Rd. NW. Authorities said he died at the Washington Hospital Center shortly after 11:30 p.m. of a bullet wound in the face.

Investigators said the incident occurred aboard the No. 94 bus near 13th and U streets NW. They declined to say what led to the shooting but witnesses said the victim and another man had been involved in a heated argument at the rear of the bus before the shot was fired.

The other man, armed with a pistol, fled the bus as about a dozen other passengers on the bus ducked for cover or ran screaming from the vehicle, police said.

The bus driver activated the vehicle's silent alarm and police officers arrived moments later. A lookout was radioed, and police arrested the suspect a short time later a few blocks from the scene. He was identified as William Bouie, 22, of 2225 12th St. NW.