Algerian troops were targeted in a terrorist attack Wednesday east of the capital that killed four soldiers and injured two others, security officials said.

The troops had been patrolling the area around Ait Yahia, south of the city of Tizi Ouzou, when their vehicle drove over an explosive device that had been planted on the road, the officials said, speaking on condition of anonymity because they were not authorized to speak to media.

Officials evacuated six injured soldiers to Tizi Ouzou Hospital and four died en route, the officials said.

Area residents, speaking by telephone, said terrorists hiding in the vicinity of the explosion had fired on the patrol after the blast.

The soldiers had been carrying out a sweep for suspected terrorist cells in the area, the officials said. The Kabyle region where the blast occurred is a known hide-out of terror groups.

There was no immediate claim of responsibility for the attack. Algeria has an active network of Islamic militants who often target troops in roadside ambushes or with bombs.

A group calling itself Al Qaeda in Islamic North Africa recently emerged from an alliance between Osama bin Laden's international terrorist network and a local Algerian Islamist movement known as the Salafist Group for Call and Combat.

The group claimed responsibility for twin suicide bombings last month in Algeria's capital that hit U.N. offices and a government building, killing 37 people, including 17 U.N. staff members. That attack was the deadliest of a string of recent suicide bombings in Algeria.

Algeria's Islamic insurgency broke out in the early 1990s, when the army canceled the second round of the country's first multiparty elections to prevent a likely victory by an Islamic fundamentalist party. Armed groups then turned to force to overthrow the government, and up to 200,000 people were killed in the ensuing violence.

Until recently, the insurgency had been dying down, with militants' ranks dwindling after military crackdowns and amnesty offers. But in late 2006, the militant group's alliance with Al Qaeda was a sign that Islamic fighters were regrouping.