A commercial helicopter has been shot down north of Baghdad, killing all eleven people aboard, including six Americans and three Bulgarians.

Bulgaria's Defense Ministry says missile fire was responsible for Thursday's crash of the Mi-8 helicopter, which is owned by a Bulgarian company. There has been no claim of responsibility.

Hours earlier, a bomb blast hit a convoy carrying foreign contractors on the road to Baghdad's airport, killing at least two people.

A US Army soldier passes by destroyed Army vehicles after a car bomb exploded near a U.S. convoy in an area of western Baghdad

Al Qaida in Iraq -- the group headed by the most-wanted terrorist in Iraq, Abu Musab al-Zarqawi -- claimed responsibility for a suicide car bombing that targeted interim Prime Minister Ayad Allawi's convoy.

The explosion happened near a police checkpoint in Baghdad, as Mister Allawi's convoy headed toward his home late Wednesday. 

In another development, television networks are showing the first images of several gruesome discoveries across Iraq.  Residents in Haditha, almost 207 kilometers northwest of Baghdad, discovered 19 bodies Wednesday, slumped against a bloodstained wall in a soccer stadium. Witnesses say the victims, all men, appeared to have been shot to death. Residents initially said the men, dressed in civilian clothes, were soldiers abducted by insurgents.

There are also still questions surrounding dozens of bodies pulled from the Tigris River and buried in a mass grave nearby.  Wednesday, Interim President Jalal Talabani said more than 50 bodies had been recovered.

He did not say when those bodies were found, but claimed the victims were hostages, seized by Sunni insurgents about 22 kilometers southwest of Baghdad.

Late last week, Iraqi and Shia officials claimed 100 hostages were abducted. But Iraqi security forces found no such evidence. And Reuters cites police as saying the Tigris bodies were discovered over the past several weeks.