Iraqi security forces have arrested Ahmed al-Alwani, a Sunni lawmaker who had been sought on terrorism charges.
Iraqi police officials say Alwani's brother and three guards were killed after they opened fire on security forces at dawn on December 28 as they arrived to arrest him.
Alwani is a prominent Sunni opposition figure and has led protests against Iraq's Shi'ite-led government.
Police say the shoot-out with Alwani's guards in the western city of Ramadi lasted for nearly an hour.
At least four soldiers and twelve more guards were wounded.
The sectarian conflict between Iraq's majority Shi'ia and minority Sunnis has escalated this year.
According to UN estimates, more than 8,000 people have been killed in Iraq since the beginning of 2013.
Based on reporting by AP and AFP