Taseer Khan, 30, and Derwaish Khan, 43, were ambushed as they were driving to work on a motorcycle in Charsadda, police said. They died instantly.
"They had no personal enmity. Both brothers were in uniform and were coming on duty. They died on the spot," Nisar Khan Marwat, Charsadda district police chief, told AFP.
The officer said the attackers fled the scene after the ambush.
Gunmen similarly killed two policemen on Saturday in Hayatabad, on the outskirts of Peshawar. Officials blamed the attack on the Taliban.
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