Islamist militants disguised as security officials killed three Tunisian policemen and a civilian  in an attack near the border with Algeria, the state news agency reported Sunday.
The agency did not name any group in the attack, Reuters reported. Tunisia's security forces have been battling fighters from the banned Islamist movement Ansar Al Sharia , whose leader Abu Ayadh al-Tunisi  has declared allegiance to Al Qaeda's North Africa wing.
State news agency TAP reported that four gunmen dressed in Tunisian security official garb killed the four and wounded two police and a border agent  just after midnight in d'Awled Manna, in the country's northwest Jendouba, according to Reuters.
The militants stole weapons and a vehicle, TAP said.
Ansar Al Sharia has proved to be one of the most hardline Islamist groups to enter the political fray after Tunisia's 2011 uprising against autocrat Zine el-Abidine Ben Ali , whose government often jailed Islamist leaders.
Tunisia has progressed in its transition to democracy after the revolt, with a new constitution praised for its modernity and elections scheduled for this year. 
But Islamist militant violence is one of the main challenges for the new caretaker government. Earlier this month, police killed seven militants armed with suicide bomb vests and explosives in a raid north of the capital, Reuters reported.
Ansar Al Sharia led by a veteran of Afghanistan's wars, was blamed for storming the U.S. embassy in Tunis in 2012  and is listed by Washington as a foreign terrorist organization, with ties to Al Qaeda in the Islamic Maghreb.