Bamako - A gun attack on a restaurant in the capital of Mali has killed four people including two Malians, a citizen of France and a citizen of Belgium, a senior intelligence official told Reuters on Saturday.Two people have been arrested over the attack at the popular La Terrasse restaurant. The motive is not known, the source said."The zone where the shooting took place is under the control of the security forces. Two Europeans and two Malians have been killed. The security forces are conducting an operation to ensure there are no other surprises," the source said.Mali's desert north sees regular political violence but the capital Bamako is largely peaceful.French forces wrested control of the north from separatist rebels and militants linked to al Qaeda two years ago but the insurgents continue to mount attacks.Mali's government signed a preliminary peace proposal on Sunday meant to end fighting with northern separatists, but the Tuareg-led rebels demanded more time before agreeing to any accord.