Baghdad (AFP) - Six pupils were among eight people killed at a Baghdad primary school Monday in what authorities said was an ammunition blast, out of a total of 16 people who died in violence in and around the capital. Just north of the Iraqi capital, six anti-Qaeda militiamen were gunned down in broad daylight and the wife of a militia commander was killed when their home was bombed. Two hospitals in the Baghdad Shia neighbourhood of Sadr City said eight people were killed in the school blast, including six pupils from the Abaa Dhar primary school for boys. Twenty-five pupils and three teachers were among 41 people wounded. A police officer confirmed the casualty toll, speaking on condition of anonymity. An Iraqi security forces spokesman said the cause of the blast was not a bomb but the accidental detonation of a cache of explosives stored within school grounds. The explosion happened inside the school while the school principal was burning garbage, said Baghdad operations command spokesman Major General Qassim Atta. Underneath the garbage was a cache of IEDs (improvised explosive devices) hidden underground by special groups. Special groups is the term given by US commanders to Shia militias they say are armed and trained by Iran. The 1:10 pm (1010 GMT) explosion, which left a crater around four metres (13 feet) in diameter, struck just outside the main entrance of the school and severely damaged three nearby houses. I just went to get my lunch when the explosion happened, said Umm Ali, who lives close to the school and suffered wounds to her arms and face. Everything was thrown into the air. I went outside to see what had happened and saw children running in all directions, the 46-year-old said. North of the capital, in Nadeem village just inside Baghdad province, six members of the Sahwa (Awakening) anti-Qaeda militia were shot dead at a checkpoint in a 9 am (0600 GMT) ambush by gunmen using silencers. Five gunmen walked towards the checkpoint and opened fire, killing six Sahwa members, said police Major Thamer Hussein. In another attack in the nearby town of Tarmiyah, bombers blew up the home of Sahwa commander Abu Mustafa, killing his wife and wounding his son and daughter, both in their teens. Abu Mustafa was not in the house when the explosion took place, said police Lieutenant Wisam Badr. A police officer said the bombers had probably planted the explosives during the night and then detonated them during the day. The US military began recruiting the Sahwa militias among Sunni Arab tribesmen and former insurgents in 2006, turning the tide in the war against Al-Qaeda in Iraq and leading to a dramatic fall in levels of violence. The Sunni fighters have been targeted in apparent revenge attacks in recent weeks, however. On Sunday, in the town of Rashad, 175 kilometres north of the capital, a Sahwa member was killed when a bomb struck his car. Three others were wounded in the attack, including the local leader of the militia, Shujaa Taji al-Rayashi, the apparent target. In mid-November, 13 members of a Sahwa-led tribe were killed by gunmen in Iraqi army uniforms in execution-style attacks west of Baghdad. Meanwhile, in the upscale Mansur neighbourhood of the capital on Monday, one person was killed and five wounded by a magnetic sticky bomb attached to a minibus, a police officer said. Violence across Iraq dropped dramatically last month, with the fewest deaths in attacks since the US-led invasion of 2003. Official figures showed a total of 122 people were killed in November.