A dust storm that cut visibility to near zero has triggered a series of chain-reaction crashes involving more than 20 vehicles on an Illinois highway, killing six people and injuring at dozens more.

Up to 60 passenger cars and about 20 commercial vehicles, including numerous tractor-trailer rigs, were involved in Monday’s pile-up on Interstate 55 in southern Illinois, a state police official said later in the day (US time).

More than 30 people were transported to local hospitals with injuries, and there were “multiple fatalities”, the official said.

Two of the trucks caught fire as a result of the crash and it was possible one had exploded, he said.

Joletta Hill, chief deputy for the Montgomery County Coroner’s Office, later confirmed at least six people were dead.

Local media posted video footage of the scene showing smashed cars and trucks crumpled against one another, some of them on the shoulder of the highway.

The clip showed one truck burning amid a thick haze of dust and smoke.

Montgomery County’s Emergency Management Agency director Kevin Schott said emergency responders found the scene difficult because of the thick dust, noting everyone’s “eyes are full of it.”

“This is a difficult scene, something that is very hard to train for, something that we really haven’t experienced locally,” he told CNN.

Mr Schott said first responders battled through thick haze to find multiple vehicles on fire and dozens of vehicles scattered across both sides of the road.

“We had to search every vehicle, whether they were involved in the accident or just pulled over, to check for injuries,” he said.

“People were upset – visibly so, understandably so.”

Video posted to social media showed dozens of cars and tractor-trailers strewn across both sides of the highway, as smoke and dust billowed.

One driver, 25-year-old Evan Anderson, said a truck turned before striking his vehicle, sparing him from even more damage.

“You couldn’t even see,” he said.

“People try to slow down and other people didn’t, and I just got plowed into. There was just so many cars and semi trucks with so much momentum behind them.”

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The state police official said the pile-up near the town of Farmersville, about 320 kilometres south-west of Chicago, was caused by “excessive winds blowing dirt from farm fields across the highway, resulting in zero visibility”.

CNN meteorologist Chad Myers said 70km/h winds – which came after weeks of dry weather – picked up the dust and suddenly made it nearly impossible to see on the short stretch of highway.

“The deciding factor today was the tilled fields,” he said.

“This was a localised event by localised conditions.”

State police said the 27-kilometre stretch of the highway remained closed in both directions several hours later.

-with AAP