BAGHDAD — A raid by Iraqi security forces on the home of a prominent Sunni member of Parliament on Saturday morning in Anbar Province set off a two-hour gun battle that left the lawmaker's brother and five guards dead, along with a soldier, Iraqi security and medical officials said.

Hours later, angry protests erupted over what Sunnis viewed as another crackdown by the Shiite-led government that alienates them from the political process by equating all expressions of Sunni grievance as terrorism.

The lawmaker, Ahmed al-Alwani, was taken into custody on terrorism charges after the raid at his home in Ramadi, in Sunni-dominated Anbar Province, which has been the scene of antigovernment protests for more than a year. Mr. Alwani has been an important supporter of the demonstrators.

The gunfight erupted when Mr. Alwani; his brother, Ali al-Alwani; and the guards opened fire on soldiers as they entered the home, according to Iraq's Ministry of Defense. In addition to those killed, about 10 others in the house were injured in the return fire, including the lawmaker's wife and a 12-year-old boy.

The raid inflamed Sunni anger toward the government and is likely to increase sectarian tensions further in a country that is teetering on the edge of a new civil war.

At a gathering of demonstrators in Falluja in Anbar, Sheikh Ahmed al-Tamimi, one of the protest leaders, said: "The war has begun. I call on young people to carry their weapons and prepare. We will no longer allow any army presence in Falluja." Armed demonstrators later carried Ali al-Alwani's coffin through the streets of Ramadi.

Prime Minister Nuri Kamal al-Maliki has warned protesters to leave their encampment in the western desert of Anbar, which he claims shelters Qaeda militants, who have gained strength over the last year. With violence at its worst since 2008, Mr. Maliki recently ordered a major military operation in the desert, and the United States has rushed new weapons and other equipment to the Iraqis to help them face the increased threat.

In a statement, the Ministry of Defense said the operation Saturday was "part of a plan to restore security, stability and target the organization of Al Qaeda."

It was not the first time the government has targeted a prominent Sunni official. Two years ago, the government sought to arrest the Sunni vice president, Tariq al-Hashimi, on terror charges. He fled and now lives in Turkey. In Iraq, he has received several death sentences.

And last year, the government targeted the Sunni finance minister, Rafe al-Essawi, arresting 10 of his bodyguards.

On Saturday, Osama al-Nujaifi, the Sunni speaker of Parliament, called the arrest of Mr. Alwani unlawful and demanded an investigation. Other Sunnis said the raid and arrest would make it more difficult for the government to successfully fight the Sunni-led Qaeda, a fight that to a large extent depends on intelligence from moderate Sunnis.