The driver of a van carrying schoolchildren home failed to yield when she collided with a semitrailer truck at a rural intersection in western Minnesota, authorities said Tuesday.

The crash injured the driver of the Hancock School District van and all seven children aboard, three of whom required hospitalization in the Twin Cities. It occurred shortly before 4 p.m. Monday in Swift County at County Roads 20 and 63 near Benson, the Sheriff’s Office said.

The 10-passenger van was equipped with seat belts, but no students were wearing them as required by law, Sheriff John Holtz said Tuesday. Up to four of the students were thrown from the wreckage, Holtz said.

The van’s driver was wearing her seat belt, he said.

Four children from the same family are among the injured. Two were taken by air ambulance to Hennepin County Medical Center (HCMC) for treatment of serious injuries, the Sheriff’s Office added.

Savannah Schlief, 14, was in critical condition as of Tuesday afternoon at HCMC, a hospital spokeswoman said. Sister Harleigh Schlief, 16, was in serious condition.

Two other Schlief children, 12-year-old Natasha and 11-year-old Blade, were in stable condition.

Gaige Sanderson, 16, has been upgraded from critical condition to satisfactory, the HCMC spokeswoman said. Korah Schroeder, 10, was in stable condition, and Braydn Sanderson, 15, was treated for his injuries and released. The Sandersons are brothers.

The van’s driver was identified as Judith Van Eps, 68, and described by the Sheriff’s Office as being in stable condition. She is listed on the district website as a paraprofessional and is the regular driver for that route, whose passengers are all open-enrollees.

Jeremy Beyer, who farms in the area, said he was driving east on County Road 20 and had the right of way when the southbound van on County Road 63 hit him. Sheriff Holtz confirmed later Tuesday that the van was required to yield.

“It looked like she was going to yield, but she didn’t stop,” said Beyer, 43. “She drove into the side of me and hit the trailer.”

Beyer, who came away a little sore but otherwise unharmed, said he was not distracted in any way at the time nor impaired by drugs or alcohol.

He said it took him 20 minutes to get out of his jackknifed truck, which ended up in the ditch with both doors damaged.

“It was another 10 minutes” before the first ambulances showed up and provided medical attention to the injured van occupants, he said.