An injured child is treated after the attacks. (APTN)

A girl wounded in the Tuesday attacks in northern Iraq arrives at a hospital in Duhouk, Iraq, on Wednesday.

The suicide bombers struck at least three places in and around the Yazidi sect town of Qahtaniya.

Iraqi officials: Truck bombings killed at least 500

• Story Highlights
• NEW: High number of deaths reported by local officials in northern Iraq
  
• Suicide truck bombs targeted mainly Kurdish religious minority Yazidi sect
  
• Yazidis stoned teenage Yazidi girl to death for being seen with Sunni man
  
• Sunnis then killed about two dozen Yazidi men in retaliation

BAGHDAD, Iraq (CNN) -- The death toll in the suicide bombings Tuesday in northern Iraq has risen to at least 500, local officials in Nineveh province said Wednesday.

Iraqi Army and Mosul police sources earlier put the number at 260, but said it was likely to rise. 320 were reported wounded.

The Tuesday truck bombs that targeted the villages of Qahtaniya, al-Jazeera and Tal Uzair, in northern Iraq near the border with Syria, were a "trademark al Qaeda event" designed to sway U.S. public opinion against the war, a U.S. general said Wednesday.

The attacks, targeting Kurdish villages of the Yazidi religious minority, were attempts to "break the will" of the American people and show that the U.S. troop escalation -- the "surge" -- is failing, Maj. Gen. Benjamin Mixon said.

The bombings highlight the kind of sectarian tensions the troop surge was designed to stop.

Al Qaeda in Iraq is predominantly Sunni, and Mixon said members of the Yazidi religious minority have received threatening letters, called "night letters," telling them "to leave because they are infidels."

"This is an act of ethnic cleansing, if you will -- almost genocide when you consider the fact the target they attacked and the fact that these Yazidis, out in a very remote part of Nineveh province, where there is very little security and really no security required to this point," Mixon said. Watch the grim aftermath of the suicide bombings »

Sunni militants, including members of al Qaeda in Iraq, have targeted Yazidis in the area before.

Brig. Gen. Abdul Karim Khalaf, an Interior Ministry spokesman, said there were three suicide trucks carrying two tons of explosives. At least 30 houses and other buildings were destroyed.

Khalaf said the carnage looks like the aftermath of a "mini-nuclear explosion." More bodies are expected to be found. See a timeline of deadliest attacks in Iraq »

The U.S. military said there were five bombings -- four at a crowded bus station in Qahtaniya and a fifth in al-Jazeera.

The massacre comes ahead of next month's report to Congress by Gen. David Petraeus and U.S. Ambassador to Iraq Ryan Crocker on progress in Iraq.

"We still have a great deal of work to do against al Qaeda in Iraq, and we have great deal of work to do against al Qaeda networks in northern Iraq," Brig. Gen. Kevin Bergner, a Multi-National Force-Iraq spokesman, said Wednesday.

The office of Iraqi Prime Minister Nuri al-Maliki blamed Sunni extremists for the "monstrous crime." He said a committee has been formed to investigate.

Ashraf Qazi, the U.N. secretary-general's special representative for Iraq, called the attack an "abominable crime aimed at widening the sectarian and ethnic divide in Iraq."

Qazi urged Iraqi authorities to bolster their efforts to protect minorities.

The Yazidi sect is a mainly Kurdish minority, an ancient group that worships seven angels, in the form of peacocks, who are subordinate to the supreme god who created the universe.

A couple of related incidents in the spring highlighted the tensions between Sunnis and Yazidis.

In April, a Kurdish Yazidi teenage girl was brutally beaten, kicked and stoned to death in northern Iraq by other Yazidis in what authorities said was an "honor killing" after she was seen with a Sunni Muslim man. Although she had not married him or converted, her attackers believed she had.

The Yazidis condemn mixing with people of another faith.

That killing is said to have spurred the killings of about two dozen Yazidi men by Sunni Muslims in the Mosul area two weeks later.

Attackers affiliated with al Qaeda pulled 24 Yazidi men out of a bus and slaughtered them, according to a provincial official.

CNN's Arwa Damon, Mohammed Tawfeeq and Raja Razek contributed to this report.

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