U.S. officials have said they are looking into it.

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"We are aware of reports that American citizens are missing in Iraq," State Department spokesman John Kirby said to NBC News. "We are working with the full cooperation of the Iraqi authorities to locate and recover the individuals. The safety and security of American citizens overseas is our highest priority."

Al Arabiya, a Dubai-based news service, reported in a tweet posted Sunday afternoon, that the Americans were taken by "militias." They were on their way to Baghdad International Airport.

The men are contractors who were taken away in a convoy by a group of gunmen Friday, according to CNN. The company they work for filed a report Sunday, an unnamed official told CNN.

There were no immediate claims of responsibility. Kidnappings in Iraq have been carried out by the Islamic State group and Shiite militias as well as criminal gangs demanding ransom payments or disgruntled employees seeking to resolve workplace disputes.