BROWN COUNTY, Kan. — A Wichita, Kan., construction worker suffered life-threatening injuries Wednesday when a semi and trailer backed over him in a construction zone on U.S. Highway 75.

The accident occurred near the intersection of 130th Road in Brown County, near the Golden Eagle Casino.

Master Trooper Jerry Clary of the Kansas Highway Patrol said Reyes C. Ramos, 34, was kneeling down pounding a nail into the concrete to tie a guide string when the truck — attached to a trailer full of asphalt — backed over him at 2:18 p.m.

“The semi driver had a load of asphalt and was backing up to load the machine,” Mr. Clary said. “He didn’t see him at all, and in fact even backed all the way down to the mill before realizing it when people started honking their horns and yelling that he ran over a guy.”

The tractor-trailer was driven by Tereso Delarosa-Robles, 46, of Wichita, a subcontractor for the road construction crew.

Mr. Clary said Mr. Ramos suffered life-threatening injuries, including a broken femur and possibly a broken back. He said the victim had labored breathing. He was first taken by ambulance to the Horton, Kan., Community Hospital, stabilized and then taken by air ambulance to the University of Kansas Medical Center in Kansas City, Kan.

The highway was shut down for three to 3½ hours while the Kansas Highway Patrol’s Reconstruction Team came to evaluate the scene, Mr. Clary said. It took longer than normal to investigate the scene, since the accident involved a commercial vehicle and the accident involved life-threatening injuries.

A condition update on Mr. Ramos was unavailable.