He got on the bus at Security Blvd and Rolling Road, which is in the County. Anywhere the busses go, this kind of thing could happen.
Groups of African American youths should be approached with extreme caution. No one is safe, especially if you go shopping in the malls or live near the Light Rail or off a major artery or whatever.
I grew up there and at 12 (50’s) got bus and street car transfers all over the city. NW Baltimore is probably the most dangerous.