A total of 23 people and four suicide bombers were killed and 14 wounded, in separate violent attacks across Iraq on Monday, police said. In one attack, gunmen broke into the office of Salahudin satellite TV channel and the nearby Iraqia official television's headquarters in Tikrit, the capital of Salahudin province, killing five staffers and wounding three others, when four suicide bombers blew themselves up in the attack, a provincial police source told Xinhua on condition of anonymity. The attack took place in the afternoon in central Tikrit, some 170 km north of Baghdad, when the suicide bombers blew up a car bomb at the entrance of the four-story TV station building, the source added. Fierce clashes broke out between the attackers and the guards, setting fire to the third and fourth floors of the building, he said. Iraqi security forces and reinforcement troops cordoned off the scene, while a police commando unit broke into the offices and retook control of the building after a clash with the suicide bombers, he added. Tikrit, the capital of Salahudin province which is dominated by Sunni, is the hometown of former President Saddam Hussein. In another separate incident, four army officers and two soldiers were killed in a mortar barrage on a military base in Abu Ghraib area, some 25 km west of Baghdad, a police source told Xinhua. The attack came as Iraqi security forces backed by helicopters were conducting a large-scale offensive against al-Qaida militants in the volatile Sunni area that stretches from west of Baghdad through the province of Anbar to the border with Syria, Jordan and Saudi Arabia. Al-Qaida militants are believed to have been responsible for blowing up a booby-trapped shelter on Saturday in the desert area of Wadi Houran near the city of Rutba, some 370 km west of Baghdad, killing up to 15 soldiers. On Sunday, Iraqi Prime Minister Nuri al-Maliki said that a Sunni anti-government sit-in camp in Anbar province had become "a base for the leadership of al-Qaida." He urged protesters "to leave the camp so that al-Qaida will stay alone." The Sunnis accused the government of marginalizing them and claimed that the Shiite-dominated security forces indiscriminately arrested, tortured and killed their sons. Also on Monday, two soldiers were killed in a roadside bomb explosion near their patrol in Akashat area near the Iraqi-Syrian border in Iraq's western province of Anbar, a provincial police source said. Meanwhile, gunmen broke into a barber shop in southern the city of Fallujah, some 50 km west of Baghdad, causing one dead, a local police source told Xinhua. Elsewhere, gunmen opened fire from their assault rifles on a pet shop in Doura district in the southern part of the Iraqi capital of Baghdad, killing four people, a police source told Xinhua on condition of anonymity. In a separate incident, three Shiite pilgrims were killed and six wounded when gunmen opened fire on their bus while travelling on a highway in southeastern Baghdad, the source said. The pilgrims were heading to the holy Shiite city of Karbala, some 110 km south of Baghdad, to observe the Arbaeen religious ritual ahead of its climax day next Tuesday. Arbaeen is the 40th day after the martyrdom anniversary of Imam Hussein, Prophet Muhammad's grandson and the third holy figure for the Shiite Muslim sect, who was killed in the battle of Karbala in 680 A.D. In Iraqi eastern province of Diyala, one Shiite pilgrim was killed and five others were wounded in a gunmen attack on their minibus near the provincial capital city of Baquba, some 65 km northeast of Baghdad, a provincial police source said. Also in Diyala, a civilian was shot dead by gunmen in the town of Hibhib, some 20 km north of Baquba, the source said. Iraq is witnessing its most fierce violence in recent years. According to the UN Assistance Mission for Iraq, 8,109 Iraqis, including 952 members of security forces, were killed in the country from January to November this year.