Gao (Reuters): At least 33 people were killed and dozens injured on Wednesday when a suicide bomber detonated a vehicle packed with explosives near a military camp in Mali 's northern city of Gao, witnesses and a United Nations peacekeeping source said.

A Reuters reporter who arrived at the camp soon after the blast , which occurred at about 9 a.m (0900 GMT), said he saw dozens of bodies lying on the ground alongside the wounded. Ambulances rushed to the scene as helicopters circled overhead. "It's terrible," Gao resident Kader Touré said. "The attack happened while they were having an assembly. I've just left the hospital where there were bodies ripped to pieces and bodies piled up."

The army put the provisional toll at 25 but a source in the U.N. peacekeeping force said at least 33 were killed. The camp was home to government soldiers and members of various rival armed groups which jointly patrol Mali 's restive desert north in line with a U.N.-brokered peace accord.

A French-led military intervention in 2013 drove back Islamist militants, including al Qaeda-linked groups, which had seized northern Mali a year earlier. However, Islamist militants still operate in the region and insecurity is aggravated by tensions between local rebel groups and pro-government militias.

French interior minister Bruno Le Roux described the blast as a "major and highly symbolic attack" in an area visited only days ago by French President Francois Hollande.