Police fired tear gas to disperse more than 2,000 demonstrators, most of them minority Shiites, who also burned a police checkpoint and broke windows at two other gas stations operated by the Pakistan State Oil Company.
The violence was inspired by the deaths of Dr. Ibn-e-Hasan and another Shiite, shopkeeper Syed Wajhi Haider — both killed Saturday by unidentified attackers who fled on motorcycles, police official Tariq Jamil said. No one claimed responsibility for the deaths.
"We believe the killings were targeted, sectarian killings," Jamil said.
The anger over the sectarian killings appeared to spill over into anti-American sentiments, with the attacks on the American-linked businesses. One protester, Ghazanfar Ali, said, "They want to dominate the whole world. They want to crush Muslims."
In recent years, Shiite and Sunni militant groups have been carrying out attacks on members of each other's sect, though most of the victims have been Shiite. The split between the two sects dates to a 7th-century dispute over who was the rightful successor to Islam's Prophet Muhammad.
Saturday's shootings almost immediately sparked violent protests in Karachi, and the riots continued Sunday as funeral prayers for one of the victims was being said at a mosque.
A mob of about 100 youths shouting anti-American slogans tossed stones and bricks at a KFC restaurant near the mosque.
The crowd then smashed windows at the Pakistani gas stations and the outlet owned by Caltex, a U.S. joint venture between Chevron Corp. and Texaco Inc. that operates in more than 60 countries.
As the doctor's funeral cortege passed the police checkpoint, protesters wielding sticks smashed the post and torched it. Police dispersed the crowd by firing several rounds of tear gas shells.
In the Malir district, where the doctor and shopkeeper worked, stores were shuttered. most people stayed at home following a night of demonstrations in which hundreds of demonstrators damaged buildings, burned tires and blocked traffic.
Last month, about 50 Shiite Muslims were killed in July by three suicide attackers in southwestern Pakistan. The attackers belonged to an outlawed Sunni Muslim extremist group, Lashkar-e-Jhangvi, which is known to have ties with the Taliban.
