The policemen were attacked when patrolling on Monday in Saada province in northwest Yemen, a local government source said.
The policemen were killed by followers of Shaikh Husain Badr al-Din al-Huthi, from the Faithful Youth organisation, who attacked their patrol at dawn in Nushur, northeast of the town of Saada, the source said, requesting anonymity.
Police and army units launched an offensive against the attackers following the ambush, but it was not immediately known if any of al-Huthi's followers were killed in the assault, in which heavy weapons were used, he added.
Earlier in March, three supporters of al-Huthi were killed while trying to flee from police after a shootout.
The supporters were speeding away in a car after exchanging fire with police at a weapons market in Saada province, north of the capital, Sanaa.
It had been the first such incident since the Yemeni government announced on 10 September 2004 that the army had killed al-Huthi.