TIKRIT, Iraq, Nov. 6 (Xinhua) -- The death toll from two bombings and a gunfire attack that hit Iraq's Salahudin province Sunday rose to 43, including four Iranian pilgrims, a provincial security source said.
In one of the attacks, a barrel filled with explosives detonated in the morning near workers who's working on a bridge in Shishin area in southern the provincial capital city of Tikrit, leaving up to 15 people killed and 35 others wounded, the source security told Xinhua on condition of anonymity.
In a separate incident, a booby-trapped car went off at a parking lot for Shiite pilgrims visiting one of their holiest shrines, known as Imam al-Askari shrine, in the city of Samarra, some 120 km north of the Iraqi capital of Baghdad, leaving 12 people killed and 23 others wounded, the source said.
Four of the deaths in the parking lot were Iranian pilgrims, the source said.
The massive blast set fire to several nearby cars and caused damage to many others at the scene, the source added.
Security authorities in both Tikrit and Samarra imposed curfew, blocked the entrances and tightened security measures for fear of more attacks, the source said.
Early in the day, gunmen believed to be affiliated to the Islamic State (IS) militant group, broke into the house of a tribal leader in Tulul al-Baj area, some 50 km north of Tikrit, and opened fire, killing 16 people, the source said.
The tribal leader and ten of his family members were among the killed, the source added.
Earlier, the source put the toll of the three attacks at 39 killed and 40 others wounded.
No group has so far claimed responsibility for the attacks, but the IS militant group, in most cases, had been behind deadly attacks targeting crowded areas, such as markets, cafes and mosques, across Iraq.
Terrorist acts, violence and armed conflicts killed 1,792 Iraqis and wounded 1,358 others in October across Iraq, the United Nations Assistance Mission for Iraq said.
Many blame the current chronic instability, cycle of violence, and the emergence of extremist groups, such as the IS, on the U.S., which invaded and occupied Iraq in March 2003.