BAGHDAD (AFP) - Bombs and gunmen killed six people in Iraq on Sunday, four of them from the same family, security sources said. The four family members - parents and two daughters in their 20s - were all shot in the head overnight by gunmen who spared a third, seven-year-old daughter, interior ministry and security officials said. "This was probably a terrorist crime, which we are investigating," said Baghdad security spokesman Major General Qassim Atta. Also on Sunday, magnetic "sticky bombs" attached to cars killed two civilians and wounded another in Kirkuk, a violence-prone, religiously and ethnically diverse northern province, senior police officials said. Meanwhile, thirty-one people were injured, seven of them by live bullets, as demonstrators clashed with security forces in the northern Iraqi city of Sulaimaniyah on Sunday, a medical official said. "There were seven policemen and 24 demonstrators among the injured, including seven protesters wounded by live bullets," said Ricot Hama Rashid, director of the city's main hospital. Two local journalists were also among those hurt in the clashes which broke out after protesters blocked the main Mowlawi street in the Kurdish city, 240 kilometres (170 miles) north of Baghdad. The city has seen nearly daily demonstrations since mid-February. Protesters have been calling for an end to official corruption, resignation of the regional government and an investigation into the deaths of three young demonstrators in clashes with security forces in February. Five people have been killed - including two policemen - and more than 100 injured during two months of demonstrations. Protests around Iraq against poor basic services such as electricity grew after uprisings in Tunisia and Egypt toppled entrenched regimes in those countries and spread across the Arab world early this year.