BAGHDAD (Reuters) - A visibly shaken Saddam Hussein was found guilty of crimes against humanity on Sunday and sentenced to hang by the U.S.-sponsored court that has been trying him in Baghdad for the past year. Two other senior aides, including his half-brother Barzan al-Tikriti, will also hang if automatic appeals fail in the coming months. His vice-president was jailed for life and three minor officials of his Baath party were sentenced to 15 years. Shortly after the verdict was read out at noon (0900 GMT) in a heavily fortified Baghdad courtroom that was once a Baath party office, clashes broke out between gunmen and U.S. and Iraqi troops in two Sunni Muslim neighborhoods of the capital. By contrast Shi'ites, the majority now in power, poured into the streets, dancing and yelling in joy that the Sunni Arab who oppressed them for three decades is now likely to be executed. Mortar rounds slammed into two districts of Baghdad, one Sunni, one Shi'ite, killing five people in all, police said. The Shi'ite prime minister, Nuri al-Maliki, said in a somber televised speech to the nation that Saddam "is facing the punishment he deserves." Maliki's government has been criticized for interfering in the case, which concerns the deaths of more than 148 Shi'ite men from the town of Dujail. The verdict, delivered in a rapid-fire, 45-minute session, was the highpoint so far in one of the great experiments in the law of war crimes since Nazi leaders were tried at Nuremberg 60 years ago. Saddam is also on trial for genocide against Kurds. QUESTIONS ABOUT COURT Yet the descent toward civil war since Saddam was overthrown in a U.S.-led invasion in 2003, and questions about the impartiality of the American-backed court, have blighted a case that the United States hoped would unite Iraqis after three decades of Saddam's rule. Underscoring the depth of sectarian divisions, in Baghdad's Shi'ite Sadr City district youths shouted "Execute Saddam!," while in his hometown of Tikrit, in the Sunni heartland, a crowd chanted old Baathist slogans such as "Saddam we will give our blood for you." Saddam's counsel said the verdict was timed to help President George W. Bush's Republicans in Tuesday's congressional elections, and had urged a delay to prevent the sentence triggering bloodshed "for generations to come." The U.S. ambassador, Zalmay Khalilzad, said "closing the book on Saddam and his regime" was a chance for Iraqis to unite. The court was set up by U.S. occupying officials who resisted calls for an international tribunal. At first the 69-year-old ousted president, who has defiantly justified killing and torturing Shi'ite opponents, refused to stand up before the judge. Eventually he rose shakily to his feet in the dock to hear the verdict and sentence read out. As chief judge Raouf Abdul Rahman spoke, Saddam, hands clenched behind his back, almost succeeded in drowning him out, yelling the Muslim battle cry of "Allahu Akbar!" (God is Greatest) and "Long Live Iraq!." NOOSE, NOT FIRING SQUAD "The court has decided to sentence Saddam Hussein al-Majid to be hanged until he is dead for crimes against humanity," the judge said, ignoring a plea made by Saddam earlier in the trial that he should face a military firing squad, not the noose. Saddam is being held at Camp Cropper, a U.S. military stockade at Baghdad airport, and any execution is likely to happen behind prison walls, like those of dozens of others of criminals this year. Judge Abdul Rahman, prompted by the defense lawyers, ordered one of the five guards around Saddam out of court for chewing gum and apparently laughing at the condemned man. Dressed in the tieless and sober black suit he has worn in court appearances, and clutching a Koran, Saddam also struck a pious note, asking Iraqis to be "forgiving" toward American invaders and any "traitors" who repented. Police said one woman was killed and 10 people were wounded by celebratory gunfire in Baghdad. When Saddam's two sons were killed in a U.S. raid in July 2003, dozens of casualties were reported from celebratory gunfire, an old Arab tradition. State television broadcast images of street celebrations, superimposed on footage of Saddam-era mass graves and killings. The main Sunni channel instead showed a soap opera. Abdul Rahman ejected former U.S. attorney general Ramsey Clark at the start of the hearing after the veteran campaigner sent him a note describing the trial as a "mockery of justice." The Iraqi High Tribunal also sentenced Awad Hamed al-Bander, former chief judge in Saddam's Revolutionary Court, to death. Former Iraqi vice president Taha Yassin Ramadan was sentenced to life in prison. A fourth local Baath party official was acquitted at the prosecutor's request. Three defense lawyers have been killed in the course of the trial, and the previous chief judge resigned over government interference. Malcolm Smart of the human rights watchdog Amnesty International said: "We don't consider it was a fair process."