( CNN ) -- Broken bodies of children . A dead mother . A wailing father . That was the scene outside of a school in the northern Iraqi city of Mosul , where authorities said more than 100 people were killed Friday in fighting between security forces and al Qaeda-backed Sunni fighters . The fighting follows news a day earlier that militants tried to take control of the city of Samarra to the south , violence spurred in part by an escalating conflict between Iraq 's majority Shiite government and a Sunni minority who claim they are disenfranchised . The violence has left hundreds dead in recent months , raising fears it could return Iraq to the level of violence in 2006 and 2007 , when bodies littered the streets . Nearly 500,000 people are estimated to have been displaced this year in fighting , primarily in the Sunni-dominated Anbar province , the United Nations refugee agency said Friday . But that number is expected to climb , said Adrian Edwards , the spokesman for the U.N. High Commissioner on Refugees . On Friday , Hares Hammadi al-Bajari was among dozens trying to flee the fighting in Mosul , where militants were attacking police stations and security checkpoints . With a round-the-clock curfew in effect that banned people from driving , Bajari , a taxi driver , set out on foot with his family to try to make it to safety in the nearby Kurdish-controlled Duhok province . `` Kurdish security forces were welcoming families , '' police Lt. Salah Othman said . But as Bajari neared the checkpoint on the outskirts of Mosul 's al-Zahraa neighborhood , according to Othman , fighting resumed . The family was forced to regroup outside a school to wait for a lull in the fighting and try again , he said . That 's when a barrage of mortars struck near the building , landing among the families . A video posted on Facebook purports to show the aftermath of the bombing . A man can be heard screaming : `` Let them see . ... See these children ? See what 's left from the mortar round ? They are targeting women , and these dead children . '' The footage shows the bodies of a number of children , including some missing body parts . CNN can not confirm the authenticity of the video . But it correlates with the description of the attack given to CNN by Othman . At least 17 people were killed in that attack , according to Iraqi health officials . Another 55 people , including 22 Iraqi police and 33 militants , were killed and 43 wounded in fighting that broke out across the city , the health officials said . Scores more were killed when gunmen and several suicide bombers attacked an Iraqi munitions storage in western Mosul , security forces said . By nightfall , Iraqi security forces had retaken control of a number of the police stations and checkpoints , authorities said . The fighting in Mosul mirrored an attack a day earlier in Samarra , when gunmen attacked security checkpoints and took control of portions of the city . The attackers are believed to be members of the Islamic State in Iraq and Syria , an al Qaeda splinter group also known by its acronym ISIS . Gunman seize Iraqi university , use students as human shields . 23 killed in clashes in Iraqi city of Samarra .
A mortar attack outside a school in Mosul leaves 17 dead , police say . The dead are families who were trying to flee fighting , police say . Nearly 500,000 people are estimated to have been displaced this year .