TUNIS, Tunisia — Armed militants operating a fake checkpoint in northwest Tunisia killed four people and wounded four others early Sunday, the Interior Ministry said.

Authorities said four men blocked the road near Jendouba, just 30 miles from the Algerian border. They stopped a vehicle and killed two of its occupants, including a prison guard, and wounded two others.

When a patrol of National Guard approached the road block around 1 a.m. the group of four militants opened fire, killing two and wounding another two before escaping, the ministry statement said.

Tunisia's Shems FM radio said the militants were disguised as members of the security forces.

Tunisia is battling armed radical Islamist groups with links to al-Qaida that use the country as a transit point between Algeria, home of al-Qaida's North African branch, and Libya, where weapons are plentiful and there is little central control.

In the past year, however, there is evidence that armed groups are now seeking the overthrow of the Tunisian government. Two left-wing politicians were assassinated by alleged Islamist militants last year.

Operations in the Tunis suburbs last month killed seven suspected militants and arrested several others.

Authorities have discovered several militant camps along the rugged region bordering Algeria.