St. Louis ? Lightning struck and killed a southwest Missouri farmer checking on his cattle Thursday and three teenagers died in a crash on a wet highway in the region, as storms pelted the Midwest and threatened a harvest already delayed by earlier rains.

Communities in Missouri, Illinois, Kansas and Oklahoma were under flash flood warnings, with some areas expected to get several inches of rain into today.

A 40-year-old farmer was struck by lightning around 9:30 a.m. in the Phillipsburg area about 175 miles southwest of St. Louis, Laclede County Emergency Management Director Jonathan Ayres said. The man’s family realized something was wrong about an hour and a half later, when the farmer didn’t come back inside, Ayres said. The man’s name has not yet been released.

A cow also was killed in the lightning strike.

Also in southwest Missouri, three teenagers were killed about 3:45 p.m. Thursday when the car they were riding in slid across rain-slickened U.S. 160 near Willard and was struck by an oncoming pickup truck. The Missouri State Highway Patrol identified the victims, all from Springfield, as Samantha B. Gossett and Brady A. Laughlin, both 16, and Abreanna McCarter, 15.

A handful of low-lying roads flooded, but there were few traffic problems, transportation officials said. No other deaths or injuries were reported.

This week’s rain was another setback for corn and soybean farmers in Missouri and Illinois, where spring rains delayed planting and the harvest is already weeks behind schedule. Falling temperatures also have brought a threat of frost.

Dave Down, a 64-year-old farmer with land near land near Peoria, Ill., has brought in only 90 of his 950 acres of corn and none of his 550 acres of soybeans.

“It’s sort of frustrating,” Down said. “Here I am, with about 10 percent of my corn picked and no beans. Usually this time of year, we’re two-thirds done.

“This whole year has been terrible,” he added. At this rate — assuming a freeze doesn’t claim his crop — “I think the women will be bringing Thanksgiving dinner out to the combines.”

In Illinois, the National Weather Service expected 2 to 4 inches of rain across parts of the southern and central sections of the state before tapering off today. Anywhere from 2 to 6 inches of rain could fall in southwest Missouri around Springfield.