Eleven people, including six Americans, were killed in a helicopter crash near Baghdad on Thursday. Elsewhere, another American contractor was killed in an attack near Ramadi, bringing the U.S. death toll on Thursday to seven.

All aboard the Mi-8 helicopter (search) were killed in the crash. The crew comprised three Bulgarian civilians, the Defense Ministry in Sofia, Bulgaria, said.

Two Fijian guards were also on board, a spokesman for Toronto-based SkyLink Aviation, the company that chartered the helicopter, said in Baghdad.

U.S. officials originally said the helicopter was contracted by the Defense Department, but the embassy in Baghdad said that was not true. The embassy did not indicate who the contractor was.

The Americans on board were civilian contractors for Blackwater Security (search), and were assisting the Bureau of Diplomatic Security and protecting U.S. diplomats in the country, a State Department spokesman said. Deputy spokesman Adam Ereli said he could not confirm what caused the crash.

Earlier, the Bulgarian Defense Ministry issued a statement saying the helicopter was struck by missile fire. U.S. officials said that could not be confirmed pending an investigation by Iraqi authorities.

The chopper, which was headed to Tikrit (search), went down about 12 miles north of Baghdad. Video on television showed burning wreckage scattered across a wide area.

The seventh American killed, also a Blackwater contractor, was traveling in an armored personnel carrier near Ramadi when an improvised explosive device was detonated. Another Blackwater contractor was injured in the blast.

Names of casualties would not be released until after families were notified, Blackwater said in a press release.

On March 13, two American security contractors working for Blackwater Security — a subsidiary of Blackwater USA — were killed and a third was wounded in a roadside bombing south of Baghdad on the main road to Hillah.

Last year, four Blackwater employees were killed in Fallujah, and their bodies were burned and mutilated. Two of the corpses were strung up on a bridge over the Euphrates River.

The deaths touched off a Marine assault on insurgents in the city.

Elsewhere Thursday, relatives of Iraqis who have disappeared in a Sunni militant stronghold known as the "Triangle of Death" gathered at a police station in Suwayra to examine photographs of the bodies of dozens of Iraqis that officials said were pulled from the Tigris River in recent weeks.

"My cousin was kidnapped by terrorists, and he has been missing for two weeks," Jawad Hashim Shael said as he scanned the photos. "We have searched all nearby areas, but we still have no information about his whereabouts."

On Wednesday, interim President Jalal Talabani announced that more than 50 bodies were recovered, saying that was proof of claims that dozens were abducted from an area south of the capital last week despite a fruitless search by Iraqi forces.

Talabani did not say when or where the bodies were pulled from the river, but he said all had been identified as hostages.

"Terrorists committed crimes there. It is not true to say there were no hostages. There were. They were killed, and they threw the bodies into the Tigris," Talabani said. "We have the full names of those who were killed and those criminals who committed these crimes."

Shiite leaders and government officials claimed last week that Sunni militants abducted as many as 100 Shiites from the Madain area, 14 miles southeast of Baghdad, and said they would be killed unless all Shiites left town.

But when Iraqi forces moved into the town of 1,000 families, they found no captives, and residents said they had seen no evidence anyone had been seized.

Madain and Suwayra are both located in the "Triangle of Death," a region south of Baghdad where there have been numerous retaliatory kidnappings. Police and health officials said victims were sometimes killed and dumped in the river.

As summer approaches and temperatures start to rise, bodies have been floating to the surface, said Dr. Falah al-Permani of the Swera district health department. He said as many as 50 bodies have been recovered in the past three weeks. But it was unclear whether they were the bodies referred to by Talabani.

After a week of stepped-up violence, the country's most feared terror group, Al Qaeda in Iraq, claimed responsibility Thursday for a suicide car bombing that targeted interim Prime Minister Ayad Allawi's convoy but did not harm the Iraqi leader.

The attack on Allawi's convoy occurred Wednesday, a day of multiple bombings and shootings in Baghdad and elsewhere that killed at least 13 people and wounded 21.

The victims included an Australian security contract worker and two other foreign nationals killed by assailants firing at their vehicle in Baghdad, Australian officials said in Sydney on Thursday.

Al Qaeda in Iraq claimed responsibility for several of the attacks, including the one on Allawi, in statements that surfaced on Web sites known for their militant content.

"Allawi escaped, but if one arrow missed its target, there are many others in the quiver," one of the statements said.

The authenticity of the claims could not be verified.

In a separate attack, a roadside bomb exploded on the highway leading to Baghdad's airport Thursday, heavily damaging three sport utility vehicles carrying civilians. Police Capt. Hamid Ali said two foreigners were killed and three wounded in the burning vehicles. But U.S. Embassy and military officials could not confirm the casualties.

Lately, much of Iraq's violence has occurred in the capital, as political leaders struggle to agree on a new Cabinet from the country's mix of Sunnis, Shiites and Kurds, nearly three months after Iraqis elected a 275-seat National Assembly.

Meanwhile, the Iraqi Defense Ministry identified 19 bullet-riddled bodies found Wednesday in Haditha, 140 miles northwest of Baghdad, as fishermen. Residents initially said they believed the victims were soldiers.

Investigations indicated the men came from the southern Diwaniya and Najaf provinces to fish in Tharthar lake when they were captured by insurgents, taken to the soccer stadium at nearby Haditha and shot, said chief ministry spokesman Saleh Sarhan. He did not say how the victims had been identified or why they might have been captured.

Residents heard gunshots Wednesday and rushed to the stadium, where they said they found the bodies.

FOX News' Bret Baier and Nick Simeone and The Associated Press contributed to this report.