At least two people were killed and eight injured in a suicide bomb attack targeting police in northern Baghdad on Wednesday.The bomber who wore an explosive vest blew himself up at a police checkpoint in the predominantly Shia district of Shula, Xinhua news agency reported.Several policemen were among the injured, a police report said.The toll could rise further as ambulances and police vehicles continued to evacuate the injured people to nearby hospitals and medical centres, the police said.A report by UN Assistance Mission for Iraq (Unami) estimated that 662 Iraqis have been killed and 1,457 wounded in acts of terrorism, violence and armed conflict since the Islamic State militant group took control of parts of Iraq in June 2014.Many blame the current chronic instability and the emergence of extremist groups on the US due to its invasion of Iraq in March 2003.