A bomb hit a bus carrying Shiite Muslims students in Pakistan's southern city of Karachi on Friday, killing one person in what appeared to be the latest attack in a rising wave of sectarian violence in the country, a government official said.

The attack came a day after Taliban gunmen in northern Pakistan forced 20 Shiites off buses, lined them up and killed them.

The Shiite university students who were hit Friday were on their way to an anti-Israel rally that is held every year at the end of the Muslim holy month of Ramadan, said Roshan Ali Shaikh, the top administrative official in Karachi. In addition to the person killed, 11 others were wounded, he said.

It's unclear if the dead and wounded were students on the bus, or others in the area when the blast occurred.

The rally was being held by the Imamia Student Organization, which represents Shiites throughout Pakistan. The students being bused to the rally were members of the organization from the University of Karachi.

Pakistan has a long history of sectarian violence carried out by extremists on both sides of the Sunni-Shiite divide. But most of the killings in recent years have been carried out by extremist Sunni militants, some of whom have links to the Taliban and al-Qaida.

Many analysts have criticized the Pakistani government for not doing enough to crack down on the violence.

The Sunni-Shiite schism over the true heir to Islam's Prophet Muhammad dates back to the seventh century.