A horrific Mother's Day weekend crash claimed the lives of five family members, including a young expectant mother and her two children. Travon Nelson, 22, was driving his pregnant partner Kristy Monroe, 22, the couple's 1- or 2-year-old son and 7-month-old daughter, and Nelson's 16-year-old brother in Missouri's north St. Louis County on Saturday night, the New York Daily News reports. KSDK and KMOV report Nelson veered off the side of the highway, overcorrected, and ended up swerving into oncoming traffic. The vehicle was then rear-ended by a van and flipped over, killing its occupants instantly. The 54-year-old driver of the van was hospitalized in serious condition. (More Missouri stories.)