Baghdad, AP—Iraqi troops on Saturday arrested a Sunni lawmaker sought on terrorism charges and killed his brother and five of his guards after they opened fire on the arresting officers, an incident that will likely to add to the nation’s sectarian tensions.

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.

Along with al-Alwani’s brother and five guards who were killed, 12 guards and four soldiers were wounded in the shooting. Six other guards were arrested, the officer said. A medical official confirmed the casualty figures. Both spoke on condition of anonymity as they were not authorized to talk to media.

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 Rafie 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-Qaeda branch believed responsible for the attacks.

Also in Anbar, Iraqi security forces this month launched a massive military operation to chase down Al-Qaeda fighters in the province’s vast dessert. Al-Qaeda 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.

The Anbar operation, which started last Saturday, followed the killing in an ambush there of a senior military commander, a colonel and five soldiers. Since it began, the government has been releasing footage with aerial shots of air strikes against moving trucks or tents in the desert, as well as videos of troops on the ground, dead bodies said to be militants killed in battle, weapons and SUVs allegedly used by the militants.

In a statement posted Saturday on a militant website, the group, known as the Islamic State of Iraq and the Levant, dismissed the military operation, saying it has not affected the Al-Qaeda fighters. The statement listed 16 purported attacks Al-Qaeda had carried out against Iraqi security forces in Anbar in the past few days.

“We bring the good news to our Muslim brothers that the coward enemy is reeling from our fire with the help of God, the mujahedeen (holy warriors) today are stronger than ever,” the statement said.

The statement’s authenticity could not independently be verified but it was posted on a website commonly used by ISIL.

Violence in Iraq in the past few months 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.