At least 14 passengers were picked out with the help of their National Identity Cards (NICs), forcibly offloaded from their bus and then shot dead by unidentified assailants on the Makran Coastal Highway in Ormara, Balochistan early on Thursday.
Two of those abducted reportedly managed to escape while 14 were shot dead and their bodies were recovered from near a local restaurant in the area.
Almost 20 armed assailants wearing Frontier Corps uniforms stopped the bus and handpicked their victims in the dead of night, Pakistan's Dawn newspaper reported, citing senior Balochistan police officers.
The victims were pulled out of a passenger bus travelling from Karachi to Gwadar and lined up after their identities were checked.
Confirming the incident, a Pakistan Navy spokesperson said that several Navy personnel were among those killed.
Armed gunmen kidnapped about two dozen passengers from two Karachi-bound coaches from Balochistan's Mastung area in 2015, killing at least 19 of them in the mountainous area of Khad Kocha.
An investigation into the incident has been launched.
The deceased included nine personnel from Pakistan Navy, one from Pakistan Coast Guard and one from Pakistan Air Force, whereas identities of the remaining three victims were not determined yet, security officials were cited as saying by Xinhua news agency.
Pakistan Prime Minister Imran Khan condemned the attacks and promised the gunmen would be brought to justice.
Meanwhile, Al Jazeera reported that an alliance of ethnic Baloch separatists claimed the responsibility for the attack.
Balochistan Chief Minister Jam Kamal said: "Terrorists are killing innocent people on the agenda of anti-state elements". He said "the nation was united and steadfast in its fight against terrorism". The attack is said to have taken place on Makran Coastal Highway in Balochistan's Ormara area.
Khan also expressed his sympathies with the families of the victims.
He further said that the country had sacrificed many lives but the "fight is far from over".
PPP Chairman Bilawal Bhutto-Zardari also condemned the killings.