Olivier Salgado, spokesman for the UN peacekeeping mission in Mali, said Monday that after a mortar attack on the camp in Aguelhok, in the northern Kidal region around 2 pm, two vehicles hit improvised explosive devices. According to preliminary information, four different attacks targeted UN personnel at the camp in Aguelhok, according to a statement released by the secretary-general's spokesman. It said a peacekeeper from Chad was killed and eight others injured. No group has claimed responsibility for the attack. Secretary-General Ban Ki-moon condemned the attacks and called for 'swift action to bring the perpetrators of these attacks to justice, the statement said. It added that attacks against UN peacekeepers 'constitute war crimes under international law.' Islamic extremists took control of northern Mali in 2012, prompting a French-led intervention that drove them from cities and towns in 2013. However, north and central Mali remain unstable, and attacks by al-Qaida in the Islamic Maghreb and linked groups against peacekeepers and security forces are common.