BAGHDAD, Iraq (AP) – Two suicide bombers tried to attack National Police Day celebrations Monday, with police shooting one dead and the other exploding his vest, killing 29 people, police and the U.S. military said. The U.S. ambassador and Iraq’s interior and defense ministers were in attendance but were far from the attacks.

An Internet statement by Abu Musab al-Zarqawi in the name of his al-Qaida in Iraq terrorist group rebuked Sunni Arabs for taking part 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 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 military statement came after a particularly deadly four-day period for Americans, with 28 killed since Thursday, including 24 troops.

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

The military said it wasn’t yet known what caused the crash 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 part of a two-helicopter team 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 suicide bombers carried out the attacks on the Interior Ministry compound, where National Police Day 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. The police major said initial reports incorrectly indicated the explosions were caused by mortar shells and one suicide car bomb.

At least 29 people were killed and 18 injured, mostly policemen, said Ala’a AbidAli, an official at al-Kindi hospital. Several police cars were destroyed, and body parts were scattered on the ground.

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 they were thought to be about a half-mile from the blasts.

Embassy spokeswoman Elizabeth Colton said Khalilzad wasn’t hurt. She said she didn’t have details on how far away he was from the explosions.