The arrested lawmaker, Ahmed al-Alwani, has been prominent among the organizers of Sunni protests against Iraq's Shiite-led government over the past year. He is sought on terrorism charges for inciting violence against Shiites who came to power after the 2003 U.S.-led invasion that ended Saddam Hussein's Sunni-led regime.
As military and security forces arrived at his home at dawn Saturday in the western city of Ramadi, al-Alwani's guards and tribesmen opened fire, prompting a shootout that lasted nearly an hour, a police officer said. A spokesman of Iraq's counter-terrorism forces, Sameer al-Showaili, told the state TV that al-Alwani surrendered after he ran out of ammunition.
Along with those killed on the scene -- al-Alwani's brother, five guards and a soldier -- 12 guards and five soldiers were also wounded in the shooting. Six other guards were arrested, the officer said. A medical official confirmed the casualty figures.
Al-Alwani's parliamentary bloc, Iraqiya, demanded his release and denounced the arrest as politically-motivated, saying it was intended to benefit the bloc's rivals in next year's national elections.
"The arrest of al-Alwani and the assassination of his brother are part of a campaign for the elections," said Sunni lawmaker, Salman al-Jumaili, who heads the bloc in the parliament. He said the Shiite-led government is "agitating sectarian tension regardless of the consequences on the future of the country."
Since last December, Iraq's Sunni minority has been staging protests against what they claim is second-class treatment at the hands of the Shiite majority. The protests have mostly focused around the western Anbar province and other Sunni areas to the north. The Sunnis have also been demanding an end to some laws they believe unfairly target them.
Al-Alwani's arrest comes a year after several bodyguards of Finance Minister Rafia al-Issawi, a Sunni, were arrested in a terrorism-related sweep, and two years after authorities issued an arrest warrant against Sunni Vice President Tariq al-Hashemi, also on terrorism charges.
Al-Hashemi, who is now living in exile in neighboring Turkey, has been given several death sentences after Iraqi courts found him guilty in absentia in multiple terrorism-related cases. He has denied the charges as politically-motivated.
The year-long Sunni protests have been coupled with a rising wave of insurgent attacks across Iraq, and the government and some pro-government officials and tribal elders in Anbar have accused the protests camps of sheltering members of the local al-Qaida branch believed responsible for the attacks.
After an ambush in Anbar killed a senior military commander and six others, Iraqi security forces last Saturday launched a massive military operation to chase down al-Qaida fighters in the province's vast dessert. Al-Qaida is believed to have made use of the war in Syria, which borders Anbar, to rebuild its organization in Iraq and to shuttle its members between the two countries.
In a statement posted Saturday on a militant website, Ira's al-Qaida branch, known as the Islamic State of Iraq and the Levant, claimed the military operation was not affecting its fighters and listed 16 purported attacks against Iraqi security forces in Anbar in the past few days.
"The cowardly enemy is reeling from our fire and with the help of God, the mujahedeen (holy warriors) today are stronger than ever," it said. The statement's authenticity could not independently be verified but it was posted on a website commonly used by ISIL.
Over the past few months, violence in Iraq has risen to levels not seen since 2008, increasing fears the country could slide back to the dark days when it was on the brink of sectarian war. According to U.N. estimates, more than 8,000 people have been killed since the start of the year.
Three separate attacks, two of them in Anbar province, killed eight people on Saturday.
In one attack, a suicide car bomber hit an Iraqi army checkpoint outside of the northern city of Mosul, killing two soldiers and wounding three, a police official said. Later, three suicide attackers stormed into a nearby police station and detonated their explosives, killing two policemen and a civilian and wounding 12 people, he added.
In the former insurgent stronghold city of Fallujah, 65 kilometers (40 miles) west of Baghdad, a bomb hit a police patrol, killing an officer and his guard, another police officer said. Two other guards were wounded in that attack.
And a policeman was killed and five people were wounded when a bomb hit a patrol in the town of Haditha, about 220 kilometers (140 miles) northwest of the Iraqi capital, the same officer said.
All officials giving the details of Saturday's arrest and attacks spoke on condition of anonymity as they were not authorized to talk to media.
Associated Press writer Qassim Abdul-Zahra in Baghdad contributed to this report.