"It was a coordinated attack and the goal was to target the FC personnel in the vehicle", Cheema said.
According to police, the attack took place early this morning in Quetta area of Languabad where the unknown attackers opened fire at the vehicle of the security personnel, leaving all four dead on the spot.
Quetta Senior Superintendent of Police Naseebullah Khan told Reuters that the "four men were shot in the head".
Security officials inspect the attack site in southwest Pakistan's Quetta on February 14, 2018. Security was tightened in the area to apprehend the culprits involved in attack while the bodies have been shifted to Civil Hospital Quetta.More news: Sexual assault cover-up claims in South Sudan rock Oxfam
The Pakistani Taliban said it carried out the attack, the second time this month it has claimed a deadly assault onsecurity forces.
Balochistan in general and its provincial capital Quetta in particular witness frequent attacks by various militant and terrorist groups.
The province, the poorest and least developed in Pakistan, has suffered almost a decade of separatist violence against the government. The province has been plagued by sectarian violence, Islamist militant attacks, and a separatist insurgency that has led to thousands of casualties since 2004.
At least seven people including five policemen were martyred in a suicide attack near a police truck on January 9, the day when Nawab Sanaullah resigned as the chief minister.