CHICAGO (CBS) — A semi-tractor trailer truck was towed away from O’Hare International Airport after it parked illegally Friday morning outside Terminal 3, prompting police to call in the bomb squad.

Police said the truck parked in an unauthorized area on the upper level outside Terminal 3 around 3:50 a.m.

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As a precaution, the bomb squad was called to the scene to help investigate, but when police searched the truck, they found nothing dangerous or unusual.

The truck was towed away by 7 a.m., according to police and the Chicago Department of Aviation. Officers could not immediately locate the driver, but police said around the driver had been found around 8 a.m., and would be questioned about the incident.

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An FBI spokesman said the agency does not believe there was a threat to the airport. The driver possibly suffered a medical problem, and was being treated. The truck was towed to a secure lot, according to the FBI.

Chicago police were taking the lead on the investigation, the FBI said.

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Police said day-to-day operations at O’Hare were not affected by the incident.