Updated 06/19/15 – 11:43 a.m.

CHICAGO (CBS) — Six people were injured Friday morning, when a semi-trailer truck crashed into 13 other vehicles, after the driver apparently fell asleep at the wheel on the Stevenson Expressway.

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The crash happened around 3:40 a.m., when an Illinois State Police trooper was conducing nightly lane closures for road construction work in the northbound lanes near 1st Avenue in southwest suburban Summit. Thirteen vehicles were stopped on the Stevenson, when a truck plowed into them.

Police said six people were taken to the hospital. Nine other people involved in the crash were evaluated at the scene, but refused further treatment.

A semi-truck crashed into 10 to 12 other vehicles Friday morning on the Stevenson Expressway in Summit, after the driver apparently fell asleep at the wheel. (Credit: CBS)

A semi-truck crashed into 10 to 12 other vehicles Friday morning on the Stevenson Expressway in Summit, after the driver apparently fell asleep at the wheel. (Credit: CBS)

Oscar Muniz was among those whose vehicles were hit.

“We just came up to the construction area, and we were stopped, and just then all heck broke loose. We got rear-ended by a semi-truck. I don’t know, about 12 cars or so. You know, a lot of people were lucky, and it could have been a lot worse,” he said. “Thank God that we got out of here alive.”

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Many of the vehicles were severely damaged in the crash, but the injuries were not considered life-threatening.

“He moved us pretty good, so it was scary,” Muniz said.

Police said the truck driver admitted falling asleep at the wheel.

All inbound lanes of I-55 were closed for about two hours after the crash, as crews towed away the damaged vehicles.

Police were questioning the driver Friday morning, but no charges had been filed as of 11 a.m.

The truck is registered to Purdy Brothers Trucking, based in Loudon, Tennessee. Purdy Brothers also has an office in Princeton, Illinois, about an hour north of Peoria.

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The company’s safety director said they were investigating the crash, and could not comment further.