BAMAKO, Mali (AP) — A suicide bomber on a scooter attacked a Malian army patrol in the troubled northern city of Gao on Saturday as other militants in a car sprayed the troops with gunfire sparking a clash that left three suspected militants and two soldiers dead, an official said.

The attack, in which four other soldiers were wounded, underscores the challenges facing the country following a French-led military intervention, which succeeded in liberating the three main towns occupied by the al-Qaida-linked groups in northern Mali. While the initial military campaign has succeeded in securing the largest population centers in the north, the extremists have found refuge in sparsely populated areas, from where they strike using roadside bombs and suicide attacks.