Unidentified gunmen armed with automatic weapons ambushed a passenger bus on the outskirts of the port city of Durban, killing at least six people and wounding 27 others, police said Wednesday.

A police spokesman said all 33 people aboard the bus, including the driver, were wounded in the attack, which occurred around 11 p.m. Tuesday as the bus headed north out of the Indian Ocean port city toward the town of Inanda. All of the victims were black.