Americans Who Vanished in Baghdad Likely Kidnapped by Militia: Source

Iraqi security forces were scrambling Monday to locate several Americans kidnapped in Baghdad over the weekend.

Ala Al-Sadr, a spokesman for the American Embassy in Baghdad, confirmed Sunday that some U.S. nationals were missing in Baghdad. He did not say when the kidnapping occurred.

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"There is a high level of cooperation between the American Embassy in Baghdad and the Iraqi security officials," Al-Sadr said.

The U.S. Embassy would only confirm that "several" Americans were missing.

Iraqi forces were looking at two main scenarios, according to a senior Iraqi security official who spoke on condition of anonymity because he was not authorized to speak to the media. The first was that the Americans and their Iraqi interpreter's car was stopped by militants in military uniform in the neighborhood of Dora, he said. There was also a possibility that the four were taken from an apartment in the same part of town.

"Iraqi officials do not want to release much information about their investigation, taking in consideration the safety of the missing Americans," he said. According to the official, three U.S. nationals disappeared on Saturday.

Iraqi officials were also working under the assumption that a Shiite militia was responsible for the kidnapping, the official added. The two most powerful Shiite militias in Baghdad are Asaib Ahl al-Haq (AAH) and the Hezbollah Brigades. A third smaller militia, Saraya al-Salam, is loyal to Shiite firebrand leader Muqtada al-Sadr.

Military officials, the Interior Ministry and the office of Iraq's prime minister did not respond to repeated requests for comment from NBC News on Monday.

Dubai-based news service Al Arabiya first reported that the three Americans had been kidnapped. The Saudi-owned pan-Arab television news channel cited its own sources.