DIVERNON, Ill. (AP/WGN) — Both lanes of I-55 reopened Tuesday morning hours after a windstorm in central Illinois causing numerous crashes that killed at least seven people Monday, police said.

Seven people were killed in a 72-car pileup late Monday morning near mile marker 76, between Diveron and Farmersville, about 20 miles south of Springfield. Multiple tractor-trailers were among the vehicles involved, two of which caught fire, Illinois State Police Maj. Ryan Starrick said.

I-55 was shut down in both directions in Montgomery County, 75 miles (120 kilometers) north of St. Louis.

More than 30 people on both sides of I-55 were transported to hospitals with injuries.

Those hurt in the crash range in age from 2 to 80 and have injuries from minor to life-threatening, police said. One of the seven people killed was Shirley Harper, 88, of Franklin, Wisconsin, police said.

Authorities held a news conference Tuesday morning and said they are seeking the public’s help to identify two of the victims killed in the crash.

State police believe one person was driving a blue Chrysler 300 and one person was driving a Hyundai, color not known. Anyone with any information is asked to call authorities at 618-346-3653.

“They were very unusual circumstances. Certainly dust storms happen, but it is not something that happens every day here in this part of Illinois or any part of Illinois,” Illinois State Police Director Brendan Kelly said at a news conference Tuesday.

The highway was closed in both directions after the late-morning crashes on Monday, a scene Gov. J.B. Pritzker described as “horrific.”

“The cause of the crashes is due to excessive winds blowing dirt from farm fields across the highway, leading to zero visibility,” Starrick said.

More than 40 troopers were sent to the scene, including members of the state police traffic crash reconstruction team, Kelly said. Those investigators are very early in their inquiry and have a lot of evidence to review and people to interview as part of their probe.

“We have a lot of science that has to be done to see what we can determine,” Kelly said.

Farmers in central Illinois, including Montgomery County, where the crashes occurred, are tilling fields and planting corn and soybeans, the region’s chief crops, said Emerson Nafziger, a professor emeritus in the Department of Crop Sciences at the University of Illinois’ Urbana-Champaign campus.

Much of central Illinois has received little rain in recent weeks, he said, and cropland that is normally wet this time of the year is dry — and with farmers active in their fields, high winds can easily send dust airborne.

Illinois ranks 26th among the states in terms of farm fields planted without tillage. Tilling aerates the soil, controls for weeds and pests and prepares the land for seed germination, but can increase soil erosion — including by the wind.

According to the U.S. Department of Agriculture’s 2017 Land Use Practices Census, 29% of Prairie State cropland was no-till. Illinois’ 22.2 million acres (898,000 hectares) of land in production ranks it 4th in the nation.

Kelly said his investigators would try to determine whether nature was the only factor. State Police Division of Criminal Investigation officers responded initially to identify bodies and contact family members, but while their work continues, Kelly downplayed the notion of criminal charges and would not speculate on what they could be.

“It does not benefit a farmer to lose a bunch of topsoil, so they have no motivation to do something that would cause this,” Kelly said. “There’s no logic to saying that someone did this on purpose and they were somehow skirting some sort of regulation, but we’re going to … follow the facts wherever they take us.”

Tom Thomas, 43, who was traveling south to St. Louis before Monday’s crashes, said after the vehicle he was in got into a crash, the only thing he could hear “was crash after crash after crash behind us.”

Dairon Socarras Quintero, 32, who was driving to St. Louis to make deliveries for his custom frame company based in Elk Grove Village, said that after his truck hit the vehicle in front of him, he exited and moved to the side of the road to ensure his safety, then returned after the chain reaction of crashes ended behind him.

Socarras Quintero said the dust continued to blow ferociously as he checked on other motorists and emergency personnel arrived. He held up his backpack, which was caked with dust even though it was inside a closed truck cab.

“We do have six individuals who have lost their lives,” Kelly said. “So we have to do everything we possibly can. At this point, this is a terrible series of converging circumstances.”

Winds were gusting between 35 and 45 mph (56 and 74 kph), the National Weather Service said.

“It’s very flat, very few trees,” meteorologist Chuck Schaffer said. “It’s been very dry across this area really for the last three weeks. The farmers are out there tilling their fields and planting. The top layer of soil is quite loose.”

Evan Anderson, 25, who was returning home to St. Louis from Chicago, said a semi turned before striking his vehicle, sparing him from even more damage.

“You couldn’t even see,” Anderson said. “People tried to slow down and other people didn’t, and I just got plowed into. There were just so many cars and semitrucks with so much momentum behind them.”

Kevin Schott, director of emergency services in Montgomery County, said it was a “very difficult scene” and one that’s “very hard to train for.”

“We had to search every vehicle, whether they were involved in the accident or just pulled over, to check for injuries,” he said, adding that people were “upset — visibly so, understandably so.”