The first act of target killing took place near Miramshah.
Family sources said that Malik Salam Khan and Malik Niaz Khan were going from Tappi Village to Miramshah when their vehicle came under fire.
Witnesses said that Malik Salam died on the spot while Malik Niaz was taken to the district headquarters hospital in Miramshah where he died during treatment.
The district administration registered a case and the investigation was under way. However, no arrest was made.
The family sources said the deceased had no enmity with anyone.
Meanwhile, two police constables were gunned down in Prowa tehsil of Dera Ismail Khan district.
Officials said that the constables, identified as Ghulam Abbas and Muhammad Bashir, were riding a motorcycle in an area in the jurisdiction of Prowa Police Station when unidentified assailants open fire on them. They both received bullet injuries and died on the spot.
Police registered a case against unidentified people.
Funeral prayers for the two constables were offered at the police line.