KARACHI, Pakistan – Assailants detonated a powerful remote-control bomb and opened fire on a convoy carrying Chinese workers in southern Pakistan Thursday, killing at least 13 Pakistanis and injuring about 30, police and doctors said.

None of the Chinese workers was hurt in the incident, which occurred in Hub, just north of the port city of Karachi, said Faizullah Korejo, Hub’s deputy police chief.

The Chinese citizens worked at a lead extraction plant in Dudhar, a town in the southwestern province of Baluchistan, and were temporarily leaving the area for Karachi due to security concerns, police said.

While it was unclear who carried out the attack, it follows a spate of violence blamed on Islamic militants that included the July 8 slaying of three Chinese men in a rickshaw workshop in the northwestern city of Peshawar.

Referring to the recent attacks on Chinese citizens in Pakistan, Chinese Defense Minister Cao Gangchuan on Tuesday urged his Pakistani counterpart to “take measures to further ensure the safety of Chinese people” in the country, China’s official Xinhua News Agency reported.

Another senior police officer said the last two vehicles of a five-vehicle convoy came under attack. Vehicles carrying about 10 Chinese engineers and workers already had passed, the official said, speaking on condition of anonymity since he was not authorized to speak with the media.

The dead included policemen and civilians along the road.

About 30 people, many in critical condition, were evacuated to a Karachi hospital, said Dr. Tariq Kamal.

An AP Television News reporter on the scene said the attack took place in the town’s main bazaar area and shattered more than 20 roadside shops. Several cars rammed into one another in the chaos that followed the explosion.

A gun battle then erupted between the surviving police and the attackers, Korejo said.

After the July 8 attack, China sent a protest to Pakistan, a close economic and military ally. In response, Islamabad vowed to step up security for an estimated 2,000 to 3,000 Chinese nationals in the country.

Officials have suggested the Peshawar attack was linked to the then-ongoing army operation against Islamabad’s Red Mosque. Troops moved in after Islamic radicals from the mosque kidnapped several Chinese women they accused of being prostitutes.

“The incident would not shake the foundation of the friendship between China and Pakistan, but I hope the government of Pakistan will take measures to further ensure safety of Chinese people in Pakistan,” Cao was quoted as telling Pakistani Defense Secretary Kamran Rasool.

A service of the Associated Press(AP)