Several loud explosions rocked the northern Mali city of Timbuktu on Sunday near military bases where one UN peacekeeper was killed and seven French troops were wounded last weekend by Islamist militants, a resident and a UN source said.

The UN source said that the UN peacekeeping mission base in Timbuktu known as the “Super Camp” was once again targeted by mortar fire, although that information could not be immediately confirmed.

Youba Cisse, a trader in Timbuktu, told Reuters he heard at least three loud detonations coming from the direction of the camp.

The April 14 car bomb and rocket attacks on the heavily fortified bases by militants disguised as UN peacekeepers marked a particularly daring assault amid an upsurge in jihadist violence in Mali and neighboring countries.

France’s defense ministry said at least 15 assailants were killed when it scrambled fighter jets and attack helicopters to respond. A peacekeeper from Burkina Faso also died in the attack.

UN peacekeeping and French military forces in northern Mali have faced near-constant attack over the past year by determined and well-armed jihadist groups seen as the gravest threat to security across West Africa’s Sahel region.