A Seattle bus driver died on Friday after he was shot while driving his bus across one of the city's many bridges. A passenger on the bus was also killed. Police say the driver was wounded by a shot fired by a passenger and died when he was thrown from the vehicle.

The dead passenger was believed to be a suspect in the shooting. A second suspect was reported to be in custody in a hospital.

Another 30 people were injured and taken to hospital. The city bus crashed through a guard rail on the Aurora Bridge, then fell 16 metres to the ground below. The bus smashed into an apartment building. One witness said "it was pretty much mayhem -- people screaming and moaning. There was blood everywhere."

Police say the driver was wounded in the arm and lost control of the vehicle. Seattle police sergeant Jim Scott said " we believe it (the shot) was fired from within the bus."

It's estimated about 30 people were on the bus when the accident happened.