A suicide car bomb exploded outside a children's hospital in western Baghdad on Monday, killing at least two people and wounding 11, including seven policemen, officials said. Police believe the bomb had been targeting a passing convoy carrying a police colonel, who was among the injured. In western Baghdad, gunmen attacked the convoy of the city's Deputy Gov. Ziad Tariq, killing three civilians and wounding three of Tariq's bodyguards, Baghdad police said. Tariq was not injured. An extremist group, the Islamic Army of Iraq, posted a video on a Web site Monday that showed an unidentified man being shot in the back of the head, and the group claimed the killing was of American adviser Ronald Allen Schulz - a native of North Dakota who moved to Alaska six years ago. In other violence Monday, gunmen opened fire on a bus carrying university students in central Baghdad, injuring two, police said, while in the south of the capital, 12 gunmen in three cars attacked a police checkpoint with rocket-propelled grenades. Two police and two civilians were injured, Capt. Haqi Mgotir of the Interior Ministry said. The string of violent attacks, including shootings and bombings, began Saturday night, shattering the relative calm since Iraq's parliamentary election last week. In a speech Sunday, US President George W. Bush praised the vote and warned against a pullout of US forces, saying that a U.S. troop pullout would "signal to the world that America cannot be trusted to keep its word." Iraqi authorities were still tallying the ballots from Thursday's election that will determine the allocation of parliament's 275 seats for a four-year term. Election official Safwat Rashid said the commission had so far received 345 complaints about the election, more than half claiming violations of campaigning rules. The complaints have to be dealt with before election results are released, a process that officials have said would take about 10 days. The big election turnout - particularly among Sunni Arabs who boycotted the vote for an interim legislature last January 30 - raised expectations that increased political participation may undermine the Sunni-led insurgency and allow U.S. troops to begin pulling out next year. But Vice President Dick Cheney, during a surprise visit to Baghdad, stressed the Bush administration did not plan a rapid withdrawal. Prime Minister Ibrahim al-Jaafari told Cheney that he estimated 70 percent of Iraq's 15 million registered voters went to the polls. At least one hardline Sunni Arab politician, Saleh al-Mutlaq, said Sunday that the turnout was a sign that insurgents are ready to participate in the political process. "By abiding to its promise not to attack the voting process, the resistance has proved that it is ready to lay down its arms if the dialogue and democratic process is genuine," said al-Mutlaq, who heads the Iraqi Front for National Dialogue.