At least seven people were killed and three others wounded in a suicide bomb attack at a crowded marketplace in a town in Iraq's western province of Anbar, a provincial security source told Xinhua.The attack occurred in the evening when a suicide bomber detonated his explosive vest at a popular market in the central town of Heet, some 160 km west of the Iraqi capital of Baghdad, the source said on condition of anonymity.The death toll could rise as ambulances, police and civilian vehicles evacuated the victims to the town's main hospital and medical centres, the source said.No group has so far claimed responsibility for the attacks, but the Islamic State militant group, in most cases, is responsible for such suicide attacks targeting crowded areas, including markets, cafes and mosques across Iraq.Terrorist acts, violence and armed conflicts killed 345 Iraqis and wounded 446 others in May across Iraq, the United Nations Assistance Mission for Iraq said.The attack came as Iraqi security forces, backed by the anti-IS international coalition, were simultaneously conducting a major offensive to dislodge IS militants from their remaining redoubt in the western side of Mosul.