American military officials have confirmed an insurgent attack on an Iraqi military outpost in Fallujah that took down an entire building and killed at least two Iraqi soldiers. Twelve others were wounded, officials said.

The attack, which took place Sunday morning, targeted a downtown hotel being used as an observation post.

Iraqi police officials put the death toll at 20. There was no immediate explanation for the discrepancy between the two reports.

According to wire reports, the attack was carried out by insurgents disguised as mechanics.

The men sneaked into a car repair shop in the ground floor of the building, planted several explosive charges, then left. Later, they detonated the explosives remotely, causing the building to collapse.

The Associated Press reported that the building was the al-Salam Hotel.

The AP quoted a police lieutenant named Khaled al-Eulaimy in reporting the higher death toll.

In a Web posting, a Sunni insurgent group called the Islamic State of Iraq claimed responsibility for the attack.

A news release issued by the U.S. Marine Corps command at Camp Fallujah said one of the wounded Iraqi soldiers was brought to a U.S. camp for medical treatment.

The other 11 were treated at Iraqi facilities, the officials said.

U.S. troops responded to the scene of the attack to help with the medical evacuation and to “conduct a post blast assessment,” the release read.

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