KARACHI, Pakistan — Armed separatists stormed the Chinese Consulate in Pakistan’s southern port city of Karachi on Friday, triggering an intense hourlong shootout during which two Pakistani civilians, two police officers and all three assailants were killed, Pakistani officials said.

The killed Pakistani civilians were a father and a son who had come to the consulate to pick up their visas to China, police said.

The brazen assault, claimed by a militant group from the southwestern province of Baluchistan, reflected the separatists’ attempt to strike at the heart of Pakistan’s close ties with major ally China, which has invested heavily into road and transportation projects in the country, including in Baluchistan.

All the Chinese diplomats and staff at the consulate were safe and were not harmed during the attack or the shootout, senior police official Ameer Ahmad Sheikh said. They were evacuated from the area shortly after and taken to a safe place.

Following the attack, China asked Pakistan to beef up security at the mission. In Beijing, Foreign Ministry spokesman Geng Shuang said that China would not waver in its latest big project in Pakistan — the China-Pakistan Economic Corridor — and expressed confidence that Pakistan could ensure security.

Pakistan’s Foreign Minister Shah Mahmood Qureshi spoke to his Chinese counterpart Wang Yi by phone and assured him that a “thorough investigation will be carried out to apprehend the perpetrators their financiers, planners and facilitators” linked to the attack on consulate, according to a foreign ministry statement.

It quoted Yi as saying that the attack was an attempt to impact Pakistan China relations and to harm the CPEC.

Pakistani Prime Minister Imran Khan also condemned the attack, describing it as part of a conspiracy.