Officials say at least 41 minority Shi'ite Muslims were killed and dozens injured after gunmen opened fire on their bus in Pakistan's southern city of Karachi.
Television channels carried pictures of a pink bus covered in bullet holes.
Police Superintendent Najib Khan told local television that 41 people had been killed.
A police officer told the media, "The gunmen stopped the bus and first fired at it from outside. Then they entered inside the bus and opened fire indiscriminately."
Pakistan has seen a rise in sectarian violence in recent years, particularly against minority Shi'a who represent around 20 percent of the country's predominantly Muslim population of 200 million.