(CBS) — A trucker on the Borman Expressway in Gary, Ind. lost one of his trailers but didn’t realize it for more than seven miles.

Indiana State Police Sgt. Ann Wojas said police may never know who sideswiped the semi, which was hauling two trailers just west of Grant Street, forcing it onto the right shoulder.

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When the semi’s driver recovered and pulled back into traffic, he overcompensated, and his rear trailer fishtailed, detached and rolled onto its side, authorities say.

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Unaware of the problem, the trucker kept going until stopped near the Toll Road interchange. The overturned trailer did not lose its load of Amazon packages but took two hours to upright.

The 2015 Freightliner is owned by U.S. Freightways Logistics of Elk Grove Village and was driven by Jeffrey R. Olgetree from Haughton, La., police said.

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