QUETTA, Pakistan (Reuters) - Unidentified gunmen killed 14 people in southwestern Pakistan after pulling them from several passenger buses, sifting through their identity cards and kidnapping them, a Pakistani official said on Thursday.

A Baluch insurgent group claimed responsibility in a statement emailed to reporters and newspaper offices.

Fighters of Baloch Raji Aajoi Saangar carried out the killings, said the group, which described itself as an umbrella body of three Baluch separatist movements in the region, but denied that ordinary passengers had been targeted.

“Those who were targeted carried cards of the Pakistan Navy and Coast Guards, and they were only killed after they were identified,” the group’s spokesman, Baluch Khan, said in the statement.

The passengers were traveling on a coastal highway from the financial hub of Karachi towards Gwadar, the Arabian Sea port town where China is building a deep-water port.

Southwestern Baluchistan province has long been plagued by violence and a stubborn insurgency, with several separatist groups and Islamist militants operating in a region that boasts vast gas and mineral resources.

Security has improved considerably across much of Pakistan in recent years but Baluchistan is still plagued by attacks, a major source of concern for Pakistani and Chinese officials who fear it will disrupt plans for a transport corridor through the province as part of China’s Belt and Road initiative.

Baluchistan Home Minister Ziaullah Langove said the dead passengers had their legs and hands tied and were found close to the town of Ormara, about halfway between Karachi and Gwadar.

“Terrorists offloaded 14 persons from different buses after checking their NICs. They took them and killed them,” Langove said, referring to Pakistani national identity cards.

Langove did not specify how the passengers were selected to be kidnapped and killed or their identities.

Ethnic Baloch separatist groups say outsiders are exploiting the region’s natural wealth at the expense of local people and have previously targeted foreigners and Pakistanis from other regions. Islamist militants have also singled out minority Shi’ite Muslims.

Prime Minister Imran Khan condemned the attack and asked for an urgent report.

“PM has directed the authorities to make every possible effort to identify and to bring the perpetrators of the barbaric act to justice,” Khan’s office said in a statement.

Pakistani media reported earlier that the militants had kidnapped the passengers from a single bus, although Langove said it was from six or seven different vehicles.