A woman hiding among Iranian pilgrims with a bomb strapped under her black robe killed more than three dozen people and wounded at least 72 others on Sunday outside a Baghdad mosque during ceremonies to mark the anniversary of the death of one of Shi'ite Islam's most revered saints. The suicide attack was the most recent in a series that has killed more than 60 people in less than a week and marred celebrations of the transfer of many security responsibilities from the US military to Iraqi forces. The attack in Baghdad's northern Shiite neighborhood of Kazimiyah came as the Iraqi military held parades to mark the anniversary of its founding 88 years ago and to celebrate the new security agreement with the United States that went into effect on Thursday. The agreement replaced an expired U.N. mandate that allowed the U.S. and other foreign troops to operate in Iraq. Under the new agreement, U.S. troops in Iraq will no longer conduct unilateral operations, will act only in agreement with Iraqi forces and they cannot arrest people without warrants. They must also vacate major Iraqi cities by June and withdraw all troops must leave by the end of 2011. It remains unclear if Iraqi security forces will manage. But Iraqi President Jalal Talabani told Iraqi army troops during a parade marking Army Day on Sunday that "the Iraqi army has gained the trust of government and Iraqi people as the army of all Iraqis." "This day will be recorded in modern Iraqi history," Talabani said after watching the first military parade since the U.S.-Iraq agreement went into effect. The parade included recently purchased US military equipment and armored vehicles. As parade took place around noon, hundreds of worshippers had gathered a few miles (kilometers) away in Kazimiyah, home to the shrine of Imam Mousa al-Kazim, one of the holiest men in Shiite Islam. The woman was among a group of Iranian pilgrims and she blew herself up just outside the gates of the mosque, a large building graced by four minarets, witnesses said. The office of Iraqi army spokesman Brig. Gen. Qassim al-Moussawi confirmed a woman wearing an explosives vest was responsible for the attack. Iraqi army and police put the deaths at 38, although the Prime Minister's National Operations Center said it was 36. Conflicting reports on the number of dead and wounded are common in Iraq in the chaotic aftermath of attacks. At least one report from the Health Ministry said the dead included 17 Iranian pilgrims, seven of which were women. There were also seven Iraqi women killed by the blast, which sent shrapnel hurtling across the crowded square. "I saw many dead pilgrims on the ground after the explosion all covered in blood, some of them Iranians," one unidentified witness told Associated Press Television News. Thousands of pilgrims from predominantly Shiite Iran visit during Ashura, celebrated on Wednesday this year. The evening before the explosion, thousands of men marched through the streets of Kazimiyah rhythmically beating their chests with bare hands and slashing their shoulders with iron chains, part of ceremonies leading up to the anniversary of 7th century death of Prophet Muhammad's grandson Hussein. He was killed in a battle on the plains of Karbala near the Euphrates River. The battle, which was part of the dispute over the religion's leadership that began after Muhammad's death, was a key event in Islam's split into the majority Sunni and minority Shiite branches. The Iraqi police and army have deployed thousands of forces to safeguard worshippers, mostly those heading to Karbala south of Baghdad. The city is home to the golden-domed mosques of Imam Hussein and his half-brother Imam Abbas. Hundreds of thousands are expected to pour into the city Tuesday and Wednesday night for the pinnacle of the pilgrimage. Maj. Gen. Othman Ali Farhood al-Ghanimy, the Iraqi army commander in Karbala, said last week that thousands of foreign pilgrims had arrived. Although the suicide attack bore all the hallmarks of the Sunni terror group al-Qaida in Iraq, which has killed hundreds of people in bombings against Ashura pilgrims in recent years, other Islamic extremist groups have used the day to stage bloody attacks. Among the bloodiest attacks during Ashura were a series of mortar attacks and bombings in Baghdad and Karbala that year 2004 which killed nearly 200 pilgrims and wounded more than 500 others. Last week, police in the southern city of Basra arrested a leading figure in a messianic Shiite cult, known as the "Soldiers of Heaven," that has battled with Iraqi and US forces during the holiday. At least 72 people died - mostly cult members - in ferocious battles with police in 2008. The group has sought to invoke chaos as a means of inspiring the return of the "Hidden Imam" - also known as the Mahdi - a descendant of the Prophet Muhammad who disappeared as a child in the ninth century. Shiites believe he will return one day to bring justice to the world. In 2007, more than 200 members of the "Soldiers of Heaven" cult were killed and 600 people arrested after battles near the Shiite holy city of Najaf as they sought to declare an Islamic state during Ashura. At least 11 Iraqi troops were killed along with two Americans, whose helicopter was shot down during the battle.