Two bombers wearing police uniforms and holding security passes tried to attack National Police Day celebrations Monday, with police shooting one to death and the other exploding his vest, killing 29 people, authorities said. The U.S. ambassador and Iraq's interior and defense ministers were present but far from the attacks.

An Internet site known for publishing extremist material from Al Qaeda in Iraq leader Abu Musab al-Zarqawi carried a claim of responsibility for the attack, saying it was in revenge for the alleged torture of Sunni prisoners at an Interior Ministry facility. The text of the entire statement was not available.

Another statement purportedly by al-Zarqawi rebuked Sunni Arabs for voting in last month's parliamentary elections, saying they had "thrown a rope" to save U.S. policy.

Meanwhile, the U.S. military said eight U.S. troops, including four Alaska Army National Guard members and four American civilians died aboard a U.S. Army Black Hawk helicopter that crashed late Saturday in northern Iraq. The military initially said only that there were eight passengers and four crew aboard.

The last few days have been particularly deadly for Iraqis and Americans. Since Thursday, at least 183 Iraqis have been killed, including 148 civilians and 35 security forces. In the same period, 28 Americans have been killed, including 24 troops.

Since Dec. 15, at least 498 Iraqis have been killed, including 355 civilians and 143 security forces, according to an Associated Press count. At least 54 U.S. troops have died in the same period.

With the latest military deaths, at least 2,207 U.S. service members have died since the war started in 2003, an AP count shows.

The military said the cause of the crash wasn't known and an investigation would take some time. The helicopter went down about seven miles east of Tal Afar, a northern city near the Syrian border that has seen heavy fighting with insurgents.

The Black Hawk was one of two helicopters providing support for the 101st Airborne Division and was flying between bases when communications were lost, the military said.

It was the deadliest helicopter crash in Iraq since a CH-53 Sea Stallion went down in bad weather in western Iraq on Jan. 26, 2005, killing 31 U.S. service members.

Police Maj. Falah al-Mohammadawi said two bombers carried out the attacks inside the Interior Ministry compound, where the police celebrations were held. The first bomber was shot by the police, although his explosives detonated. A second bomber also detonated his explosives, al-Mohammadawi said.

One bomber wore the uniform of a police major and the other was dressed as a lieutenant colonel, an Iraqi police officer said on condition of anonymity because he wasn't authorized to speak to the media. The two had passes that enabled them to get through checkpoints and into the compound, the official said.

At least 29 people were killed and 18 injured, mostly policemen, said Ala'a AbidAli of al-Kindi hospital. Body parts were scattered on the ground.

The bombs exploded several hundred yards from the celebration.

U.S. Ambassador Zalmay Khalilzad, Interior Minister Bayan Jabr and Defense Minister Sadoun al-Dulaimi were among hundreds watching a parade of marching soldiers, police patrols and military equipment, but the attacks didn't affect the parade and none of the officials was hurt, said Lt. Col. Barry Johnson, a U.S. military spokesman.

Sunni Arabs expressed anger over a raid by U.S. troops on the headquarters of the Association of Muslim Scholars, a major Sunni clerical group. They said they would hold a special ceremony Tuesday at the Umm al-Qura mosque, which was raided early Sunday. The ceremony was organized by the main Sunni Arab Iraqi Accordance front and the Iraqi Islamic Party and would also mark the start of the four-day Islamic feast of Eid al-Adha.

The military said the raid came after a tip that there was "significant terrorist related activity in the building," and six people were detained. The association is thought by some to be close to some insurgent groups.

"The violations of the occupation forces are continuing and they are endless. The raid on the Um al-Qura mosque is the most recent example," said Muthana Harith al-Dhari, a spokesman for the Association.

In other violence Monday, according to police:

-- Gunmen assassinated an investigative judge in Kirkuk.

-- In Baghdad, gunmen fired on three people working on the country's de-Baathification commission, killing one.

-- An Iraqi intelligence officer and a doctor were slain in separate attacks.

-- Five bodies, bound and blindfolded, were found shot to death in Baghdad late Sunday.

-- A car bomb exploded west of Baqouba, killing two civilians.

Ibrahim Bahr al-Uloum, who resigned as oil minister last week over increases in consumer fuel prices, has again resumed his old post after the prime minister and president asked him to come back, Iraq's Council of Ministers said.

The Internet statement by al-Zarqawi was posted Monday on an Islamic Web site known for publishing extremist material. The authenticity could not be confirmed, but the tape sounded like the Jordanian-born leader of the group.

"This is a call to the Sunnis, in general and the followers of the Islamic Party in particular," al-Zarqawi said, referring to the Islamic Party in Iraq. The party is the biggest political home for Iraq's Sunni Arabs, with Mohsen Abdul-Hamid its spiritual leader.

"Where are you being led to? Don't you fear God?" al-Zarqawi asked.

Referring to the Dec. 15 elections, he said: "At the time, it was very clear to everyone that the crusader enemy was losing, and then you threw a rope to save him."

Al-Zarqawi accused the Islamic Party and Sunnis of collaborating with the United States and said those who voted in the parliamentary elections were "hypocrites."

He asked for divine punishment: "God, curse the leaders of the Islamic Party and those who collaborated with them."

He said the insurgents could have disrupted the elections, "but we did not do it to avoid killing some of the Sunnis who were confused" over whether to take part.

He also said the United States' announcement last month that it will withdraw some troops from Iraq this year was a victory for the Islamic forces.

Three senior members of the Islamic party declined to comment.

Election results will be released after the Islamic holiday, said Hussein Hindawi, a member of Iraq's electoral commission. Officials said they were still auditing returns from about 50 ballot boxes.

Adnan al-Dulaimi, the leader of Iraq's main Sunni political group, said after meeting President Jalal Talabani on Sunday that significant headway had been made in forming a government of national unity. Al-Dulaimi said Iraq's two Kurdish leaders, Talabani and Kurdistan regional President Massoud Barzani, have been talking with other groups on a coalition government.

Their efforts seem to have forged an understanding between the main Shiite religious bloc and al-Dulaimi's group -- which represent two traditionally hostile camps whose enmity often threatens to plunge Iraq into sectarian warfare.

Talabani said Saturday that Iraq's political groups could form a coalition government within weeks -- and some experts say it could be formed next month. Forming a viable broad-based government is a key American goal because if it includes Sunni Arabs, it could help defuse the insurgency.

The U.S. military released more details about how a French hostage Bernard Planche was freed Saturday, saying his captors fled as Iraqi army soldiers searching for weapons caches neared a farmhouse west of Baghdad and he ran to soldiers at a nearby checkpoint. Police said Sunday that Planche had been thrown out of a car nearing a checkpoint.

Planche, 52, who was working for a non-governmental organization he started himself, was abducted Dec. 5. The Defense Ministry in Paris said Planche was returning to France.