It appears the suicide truck bombings targeted members of the Yezidi religious sect, an ancient pre-Muslim community that inhabits northwestern Iraq, near the border with Syria.
Reports say at least four trucks were driven into several Yezidi villages on the evening of August 14 and detonated almost simultaneously.
The worst scenes of carnage came in the village of Khahtaniyah, where several of the trucks exploded at a crowded bus station.
There are fears the death toll could rise, as more victims are believed buried under the rubble of dozens of collapsed buildings. U.S. military helicopters have been helping the rescue effort by flying victims to hospitals in the larger towns.
The incident is one of the bloodiest in four years of fighting in Iraq. RFE/RL's Radio Free Iraq correspondent Faris Omar says Yezidis have been targeted by terrorists before, but not on a massive scale.
Omar says that threats have increased against this ethnic-Kurdish minority since a young Muslim convert was stoned to death in April.
"There was recently an incident involving a Yezidi girl who converted to Islam to marry her Muslim lover," he says. "She was killed in public, and this was used by terrorist groups and other armed groups as a pretext to increase their attacks on the [Yezidi] community, on the grounds that this community is perceived as infidels and devil worshippers."
The ancient Yezidi religion is a blend of Islam, Christianity, Zoroastrianism, and Judaism. Some Muslims consider the Yezidis to be infidels.
The accusation of devil worship stems from the fact that they venerate an archangel who is believed to have fallen from grace and become the devil.
No one has claimed responsibility for the attacks. But suspicion fell on the Al-Qaeda terror network, or related insurgent groups. AP reported that an Al-Qaeda-linked Iraqi group distributed leaflets in the area last week, warning of a coming attack because the Yezidis are "anti-Islamic."
Radio Free Iraq's Omar notes that in recent months terrorist groups have moved away from Baghdad because of the intensifying U.S. security sweep around the Iraqi capital.
"Operations carried out by the multinational forces apparently have driven terrorist and other insurgent groups out of the areas covered by these operations," he says. "And now it seems they are going after 'soft targets,' and it seems the Yezidi community -- which inhabits relatively isolated areas in the province of Ninawa -- could be such a 'soft target.'"
In comments to Radio Free Iraq, London-based defense and security consultant Charles Heyman points out the difficulty of assuring security throughout Iraq. He says the 160,000 or so coalition troops presently deployed are not nearly enough.
"If you really wanted to ensure proper security right around Iraq, you'd need at least 1 million troops, and that's an estimate based on all the counterinsurgency campaigns of the last 50 years," Heyman says.
He says it is possible to draw units from elsewhere in Iraq to reinforce those in the north. But that could leave the other areas vulnerable, as softer targets in their turn.
Washington has condemned the attacks as "barbaric," with State Department spokeswoman Dana Perino pledging that the United States will help Iraqi forces to overcome "vicious" terrorism.
Five U.S. Soldiers Die
In other news, the U.S. military said five U.S. soldiers died in a helicopter crash August 14 west of Baghdad.
The military said the helicopter was conducting a routine postmaintenance test flight when it went down near an air base in restive Al-Anbar Governorate. The cause of the crash is under investigation.
The crash brings the number of U.S. military killed in Iraq since March 2003 to at least 3,700.