Chadwick graduated from Thomas Jefferson High School in 2010. Weinfurtner graduated from Abraham Lincoln High School.
The two vehicle crash happened on "Old Lincoln Highway" around 11:30 Saturday night.
Several other people were taken to the hospital with minor injuries.
The Pottawatamie County Sheriff's Department is investigating the crash.
Viewers with disabilities can get assistance accessing this station's FCC Public Inspection File by contacting the station with the information listed below. Questions or concerns relating to the accessibility of the FCC's online public file system should be directed to the FCC at 888-225-5322, 888-835-5322 (TTY), or email@example.com.