Weather blamed for chain reaction pileup on Kennedy Expwy.

CHICAGO (WLS) -- A multi-vehicle chain-reaction crash caused a major pileup on the Kennedy Expressway Sunday morning, forcing the closure of all inbound reversible lanes as crews worked to clear the wreckage.

Illinois State Police opened the express lanes early Sunday evening.

The pileup involved 39 vehicles on the inbound express lanes between Armitage and North and prompted a large response from first responders prepared for the worst, although no serious injuries were reported.

PHOTOS: Car crashes close inbound Kennedy express lanes

"The visibility was so bad," said Kalie Duffy. "As soon as it cleared, boom, there are cars all over and before you know it they're all smashing along the side."

It was just after 10 a.m. when Duffy, her 3-month-old son Miles and her husband were driving into downtown when they became one of the vehicles that piled up on the Kennedy Expressway's reversible lanes near North Avenue.

"Everyone started spinning out of control," said Justin Giles. "One thing led to another and everyone's piled up now."

"I looked up and it was there," Mara Devlin said. "There was nothing you could do."

More than 75 personnel from the Chicago Fire Department responded to the scene, including several ambulances. Twelve people had to be hospitalized, including one firefighter, who slipped and fell on the ice, but none of the injuries were serious.

"It could have been a lot worse," said Chief Don Hroma, Chicago Fire Department. "The snow obviously played a role in this accident."

It took over two hours for IDOT to clear the lanes enough to allow traffic to begin moving. While many of those involved in the pileup just waited in their cars until they could be towed, others were transferred into CFD vehicles that were temporarily turned into warming buses.

ROAD CONDITIONS SLIPPERY IN NORTHERN SUBURBS

Road conditions were also slippery in the northern suburbs with crashes and spinouts along the Edens Expressway.

There have been no reports of serious injuries, but body shops may see an uptick in business. All along the North Shore, people and plows were out working to clear streets and sidewalks.