BAGHDAD (Agencies) - A suicide bomber sneaked into a luncheon gathering called by the leader of a local tribe, killing 30 people and wounding 110 on Friday, police said. The blast in Youssifiyah was the deadliest attack in Iraq since a suicide bomber killed 55 people at a cafe in Kirkuk on Dec 11. Youssifiyah is in the Sunni-dominated region south of Baghdad once known as the Triangle of Death because of its extreme violence. The bloodshed declined markedly in 2008, but violent rivalries persist throughout Iraq. The bombing was at a meeting hall adjacent to the residence of Sheik Muhammad Abdullah Salih, head of the Sunni al-Garaqul tribe. Police, who spoke on condition of anonymity because they were not authorised to release information to the news media, said the sheik had invited tribal senior figures and other members to lunch. The bomber was an outsider who managed to get into the house, police said. A witness said he and a friend were standing a few yards from the entrance to the meeting room when the bomber blew himself up. "What an aftermath we saw - shattered glasses mixed with blood, everybody on the ground, a bad smell, blood, remains of bodies stuck to the wall," said Ismael Abu Ayab al-Qaraghuli. Also Friday, gunmen killed two people when they opened fire on a checkpoint manned by members of the Sons of Iraq in Jurf al-Sakhar, police said. Four other people were reported wounded in the attack 40 miles south of Baghdad. The Sons of Iraq consist of Sunni insurgents and tribesmen who turned against Al-Qaeda in Iraq and joined the US military in the fight against the group. A Defence Ministry source said the bombing took place at about 2pm (1100 GMT). Attacks of all types are down sharply across Iraq in recent months although insurgents are still able to strike throughout the country, US commanders say. Throughout Iraq in December a total number 316 Iraqis were killed in political violence, the lowest monthly death toll in nearly three years, according to official figures released on Thursday. In all, 6,772 Iraqis were killed in Iraq last year, down from 17,430 in 2007. The situation appears to have stabilised across the country but violence, mainly through bomb attacks and assassinations, remains an almost daily occurrence, though usually on a smaller scale than previously.