According to Dawn, motorcyclists opened fire on acting SP Investigation Mohammad Ilyas's car while he was travelling in a car along with his family.
Along with Ilyas, his wife, son and six-year-old grandson were killed in the firing.
However, his four-year-old granddaughter was injured in the attack and rushed to the civil hospital in Quetta.
Earlier in the day, at least 15 bullet-riddled bodies were discovered in Balochistan's Kech district.
A senior administration officer has said that the Levies force found the bodies in the Gorak area of Tehsil Buleda.
"All the victims (had) received multiple bullets from a close range," he said. (ANI)