The death toll from a series of suicide attacks on Iraq's Yazidi sect on Tuesday continues to rise.  Officials now estimate at least 400 people were killed and hundreds more wounded when four truck bombs exploded in this normally peaceful part of northern Iraq.  U.S. and Kurdish officials say the attack is most likely an attempt to incite violence between the minority Yazidi sect and local Muslims.  VOA's Brian Padden reports from the Kurdish city of Irbil.

The truck bombs flattened hundreds of homes, trapping hundreds of people in the rubble.

The director of operations for the senior military staff in Washington, Lieutenant General Carter Ham, told a Pentagon news conference U.S. forces are helping with search and recovery efforts in the wake of the attacks, and are providing medical treatment and supplies. 

He says they are also working with Iraqi authorities to determine who is responsible.

"We don't yet know who did it, but certainly has the markings of an al-Qaida in Iraq type of attack," he said.  "They've made it known that they wish to attack non-Muslims, so that may be a part of this.  It may be in part [that] it is just their nature to attack [the] innocent and vulnerable as an effort, I suppose, to convey that there isn't security across the country."

Ido Babasheikh, Iraq's presidential advisor for Yazidien affairs, says this bombing is another example of Islamic extremists trying to incite violence among religious groups in Iraq.  

"We think that this crime is not against the Yazidiens, just the Yazidiens, it's against all the communities of the Iraqi society and the Iraqi community and against all humanity in this region," he said.

Hadi Ali, with the Kurdistan Islamic Union, says this attack fits the Sunni militant pattern of trying to spark fighting among different groups. 

Ali says just look at how they work.  They set off many explosions in Baghdad and Kirkuk, and other places.  He says they always find an excuse to attack.

Officials are concerned about increased tensions between Yazidi and Muslims in northern Iraq.  The military presence in these areas has been increased and a curfew set in place.