KARACHI, 4 October 2003 — At least six people were killed when gunmen opened fire on a bus carrying employees of Pakistan’s space agency in Karachi yesterday. Six others were wounded.

Witnesses said the attack occurred as about 20 workers were on their way to a mosque for Friday prayers. The gunmen, who were on motorcycles, fled after the shooting.

Two of the six wounded were in critical condition. The bus belonged to the Space and Upper Atmosphere Research Commission, which is charged with developing satellite technology. Most of the victims were Shiites who worked for the commission.

Nobody claimed responsibility, but suspicion fell immediately on one of several Sunni extremist groups that have killed hundreds of minority Shiites in recent years. The attack occurred in a neighborhood in the west of the city, near the port.

Police said an investigation was under way, but no arrests had been made.

Hasan Turabi, a prominent Shiite leader, condemned the attack and asked the government to provide better protection for the community. “It is the duty of the government to protect us from these terrorists,” he said. Shiite suicide attackers stormed a mosque in the southwestern city of Quetta in July, killing some 50 worshipers. A month earlier, gunmen opened fire on Shiite police trainees in the town, killing 11.