Two children and two adults had to be helicoptered to the hospital after they were critically injured in a head-on crash Tuesday night in north Alabama.

The wreck occurred just before 6 p.m. Tuesday on Highway 243 near Block Church Road in Franklin County, Franklin County Sheriff’s Office Sgt. Kyle Palmer told WAFF.

The victims were each transported in a medical helicopter to Birmingham for treatment of their injuries, the outlet reported.

The Alabama Law Enforcement Agency is investigating the cause of the wreck, according to WHNT.