Iraqi police said Tuesday they were investigating reports that at least 20 people were kidnapped from a convoy of cars and minibuses on a highway north of Baghdad.

Police were interviewing witnesses to the alleged incident, but had few details about the alleged kidnappings, said an officer at the Joint Cooperation Center in the city of Tikrit, 80 miles north of Baghdad.

The incident reportedly occurred Tuesday afternoon as the vehicles were traveling northbound near the town of Tarmiyah, 30 miles north of Baghdad, said the officer, who spoke on condition of anonymity for fear of reprisals.

The highway running from Baghdad to Tikrit is considered one of the most dangerous in Iraq, with frequent robberies, abductions and attacks on vehicles with improvised roadside bombs. It runs through the heart of the Sunni Arab insurgency against U.S. forces and their Iraqi allies.

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Witnesses told police that a number of unidentified gunmen stopped vehicles including two cars and three minibuses, forcing passengers off, the officer said. He said he had no other details on the incident and didn't know how many people might have been kidnapped.