The shooting took place in northern Baghdad's Shaab neighborhood, known as a Shiite militia stronghold, as the driver was collecting employees to go to work at Rasheed bank, police said. U.S. troops fired when the bus reached the U.S. roadblock and tried to drive through, police and hospital officials said.
The dead and two injured were taken to Kindi Hospital, hospital officials said.
All the officials spoke on condition of anonymity because they were not permitted to release information about the shooting.
Shaab is the same neighborhood where masked gunmen reportedly killed 11 relatives of a journalist critical of the Iraqi government on Sunday. The Iraqi Interior Ministry, however, said it could not confirm the earlier deaths.
An American military spokesman said the U.S. was aware of the report about Tuesday's shooting but had no immediate details.