Five suicide bombers struck Shiite marketplaces in northeast Baghdad and a town north of the capital at nightfall, killing at least 125 people and wounding more than 150 in one of Iraq's deadliest days in years. The savage attacks Thursday came as a new American ambassador began his first day on the job, and Senate Democrats ignored a veto threat and approved a bill to require US President George W. Bush to start withdrawing troops. At least 181 people were killed or found dead Thursday, which marked the end of the seventh week of the latest US-Iraqi military drive to curtail violence in Baghdad and surrounding regions. The suicide bombers hit markets in the Shiite town of Khalis and the Shaab neighborhood in Baghdad during the busiest time of the day, timing that has become a trademark of what are believed to be Sunni insurgent or al-Qaida suicide attackers. Three suicide vehicle bombs, including an explosives-packed ambulance, detonated in a market in Khalis, 50 miles north of the capital, which was especially crowded because government flour rations had just arrived for the first time in six months, local television stations reported. At least 43 people were killed and 86 wounded, police said. In the north Baghdad bombings, two suicide attackers wearing explosives vests blew themselves up in the Shalal market in the predominantly Shiite Shaab neighborhood. At least 82 people were killed and 102 wounded as they jammed the market to buy provisions on the eve of the Muslim day of rest and prayer. The carnage in Iraq cast a shadow over Ryan Crocker's first day as ambassador. He takes over in the midst of the US-Iraqi security sweep, for which Bush committed nearly 30,000 additional troops to dampen what had become uncontrollable violence in the capital. The US Senate's rare rebuke to a wartime commander in chief came in a 51-47 vote to provide $123 billion for the wars in Iraq and Afghanistan. Senators also ordered Bush to begin withdrawing troops within 120 days of the bill's passage, and set a nonbinding goal of ending combat operations by March 31, 2008. "President Bush's policy is the right one. There has been progress; there is also much more to be done," the 57-year-old Crocker said at his swearing in at the American Embassy in Saddam Hussein's former Republican Palace, which is now in the heart of the heavily guarded Green Zone. Violence has increasingly erupted in towns and cities outside the capital in recent weeks, as insurgent fighters take their fight to regions where US and Iraqi forces are thinly deployed. The US military and its diplomats have voiced cautious optimism about the sweep and emphasized that the full American surge force would not be in place until June. Crocker brought the same message. "All of this will be very hard. But if I thought it impossible I would not be standing here today. I pledge my full support to this mission and to the people of Iraq, and I know you will do the same," he said. Crocker, an Arabic speaker, is among the most experienced US diplomats in the Middle East. He had been ambassador to Pakistan since 2004 and served as ambassador to Lebanon, Syria and Kuwait, with other assignments in Iran, Qatar and Egypt. In 2003, he was assigned to the Baghdad embassy when Iraq was being run by the Coalition Provisional Authority. In 1983 he was thrown against a wall but not seriously hurt when the American Embassy in Beirut was hit by a car bomb. In 1998, when he was in Damascus, the ambassador's residence was overrun by rioters. Crocker was not hurt. The Shaab neighborhood was one of the first that US and Iraqi forces tackled when the security crackdown began Feb. 14. It was also the scene of a bombing nearly two weeks ago in which officials said a car bomber used children as decoys to get near the busy complex of shops and street vendors. At Imam Ali hospital in the poor Shiite Sadr City neighborhood, where many of the Shalal wounded were taken, cries of pain and grief filled bloodstained corridors. Salam Hussein, who was near the Shalal market when the bombers struck, said two of his relatives were killed and three others were wounded. He said most of the victims were women and children, including six siblings. "I saw headless children and body parts everywhere. I brought four wounded to the hospital. But resources there are very limited. The refrigerators at the morgue are full. It's a disaster," he said at the hospital. Nahid Abdul-Ameer, who runs a soft drink stand about 100 yards from the market, said he saw the two bombers explode their vests at the same moment. He was cut by flying glass but was able to help with carrying away the dead and wounded. "People went out to shop today in large numbers. They had a false sense of security," he said. "People were removing dead bodies on pushcarts normally used for cases of vegetables and fruits," he said. Prime Minister Nouri al-Maliki, whose backing is dropping even among fellow Shiites, issued an angry statement pledging to bring bombers and their backers to justice. "We call on you (Iraqis) not to allow the evil ones to triumph and to cooperate with your armed forces. ... Justice will reach them sooner or later," he said. On Wednesday, Shiite militants and police went on a shooting rampage against Sunnis in the far northwestern city of Tal Afar, killing as many as 70 men execution-style. The killings were triggered by twin truck bombings there the previous day that killed 80 people and wounded 185. The Islamic State in Iraq, an umbrella group of insurgent and terror groups - including al-Qaida - claimed responsibility for the Tal Afar bombing attack in an Internet statement.