A tired driver who told authorities he might have fallen asleep crashed into an oncoming vehicle Sunday in Christiana township, with four people injured, one critically.

The crash occurred at about 11 a.m. on Hwy. 14 west of Westby, according to a news release from the Vernon County Sheriff’s Office in Viroqua.

Kody Green, 18, La Crosse, was driving east on 14 when his vehicle crossed the center line and struck an oncoming  westbound vehicle driven by Marisela Reyes-Gonzales, 32, Evansville.

The Reyes-Gonzales vehicle spun around, overturned and came to rest on its top along the westbound shoulder.

Green’s vehicle struck a mailbox and came to rest, upright, in a hay field along the highway’s north side.

Ana Maria Reyes-Gonzalez, 38, Fitchburg, a passenger in the Marisela Reyes-Gonzales vehicle, was flown by medical helicopter to Gundersen Health System in La Crosse in critical condition. Another passenger, Antonio Carrillo Maya, 49, Madison, suffered non-life-threatening injuries and was taken to Gundersen Health System by ambulance.

A 13-year-old girl in the Marisela Reyes-Gonzales vehicle was taken to the hospital, checked for possible injuries and released. Two younger children in safety seats were not injured.

Ana Maria Reyes-Gonzalez and another adult in the vehicle were not injured.

Green sustained possible injuries but refused medical treatment at the scene.

According to the release, Green also reported swerving to miss striking a deer.

The crash is under investigation.