The driver of a pickup truck involved in a fatal crash on Interstate 29 in Council Bluffs apparently fell asleep at the wheel, Council Bluffs police said Tuesday.

Omahan Scott Billings, 46, and his three children were on their way home from a family vacation at the Lake of the Ozarks about 6 p.m. Sunday when their 2009 Chevy Silverado came down an embankment off westbound Interstate 80 and hit a Ford Escort head-on that was headed south on I-29.

The Escort ended up on its top in a ditch. The truck landed on its side.

The Escort's driver, Pamela Mahoney, 49, died at the scene. Her 19-year-old daughter, Colene Mahoney, died Monday at the Nebraska Medical Center.

Billings and his children, ages 15, 14, and 4, were treated at Mercy Hospital in Council Bluffs and had been released by Tuesday. No charges had been filed, police said

Police Sgt. Jason Bailey said that shortly before the crash, the Mahoneys, of Carter Lake, had been at Creighton University Medical Center to visit Colene Mahoney's boyfriend, who was injured in an automobile crash earlier in the weekend.