A security source told AFP the men were killed "on the road between the towns of Rafah and El-Arish in north Sinai when the assailants forced the pick-up they were driving to stop, made the four policemen get out and opened fire on them".
The source added that the attackers then fled into the desert in a 4x4 vehicle.
This is the second attack on the same day in the restive peninsula. Earlier on Saturday, a failed attack targeting a police officer near his house resulted in the killing of two men accompanying the officer who survived unscathed.
Also, elsewhere in the city on Saturday morning, a shootout took place between unknown gunmen and security forces near the western entrance of the town, leaving no casualties.
Since the army's ouster of Islamist president Mohamed Morsi last summer, terrorism has spiked in the already lawless peninsula killing hundreds —mostly policemen and troops
The army is waging a broad campaign in the underdeveloped Sinai Peninsula to root out Islamist militants who say the violence is in retaliation for a crackdown on Islamist supporters of Morsi that killed hundreds and jailed thousands of others since Morsi's overthrow.