MILFORD, Neb. (AP) — Authorities are investigating an eastern Nebraska crash that killed one woman and critically injured another woman.

The Seward County Sheriff’s office says the crash happened around 5:45 a.m. Sunday on Highway 6 near Milford.

An eastbound Mazda pickup truck driven by a 45-year-old Lincoln woman collided with a minivan driven by a 20-year-old Milford woman.

Investigators have not determined what caused the crash, but the sheriff’s office said speed was a factor.

The Lincoln woman died at the scene of the crash. The Milford woman was flown to a Lincoln hospital in critical condition.

Authorities did not immediately release the names of both women.