Officials say the accident took place at approximately 2:30 P.M. on Highway 150, north of West Union and south of Nature Road.
A 2010 Chevrolet Impala was traveling northbound on Highway 150 when it crossed the center line and crashed head-on with a semi-truck heading southbound.
Terri Westfall, 65, of North Liberty, Ashleigh Rensing, 18, of North Liberty, and a 9-year-old were all declared dead at the scene.
A 15-year-old was also injured and admitted to a local hospital.
The accident is being investigated. It is yet to be known that what caused the crash.