Friday night family members of the victims tried to cope with the tragedy.
It's the latest tragedy for the Jennings family. Just four months before the mother and son were killed in Thursday night's crash, David Jennings, a husband and father, died of cancer.
"The whole family is gone now basically," said Norman Hansen, the victims' brother and uncle.
Investigators say it was a dark stretch of road on I-94 near Paris, Wisconsin where Patrick Jennings came to his mother's aid Thursday night after she got a flat tire driving home from a business meeting in Milwaukee. There were no flares or markers to let oncoming vehicles know that there was a car stalled on the shoulder.
But police say there was no reason for Clara and Patrick Jennings to be hit.
"The car that struck them veered off the roadway because they were in the shoulder area, although they were close to the roadway," said Lt. Paul Falduto, Kenosha County Sheriff's Department.
Both mother and son were killed instantly, as the 23-year-old's girlfriend watched in his car parked some 200 feet behind his mother's.
Hansen, Clara Jennings' brother, spoke to ABC7 on Friday from the Gurnee house the Jennings' called home for the last 25 years.
"He was still in school, living at home while he finished school...My sister was contemplating retiring in the next year or so and looking forward to travelling and other things," said Hansen.
Investigators have interviewed the driver of the car that hit the Jennings. She and her passenger are also hospitalized. They say alcohol was not involved, but they do expect some sort of citation to be issued once the investigation is finalized.
According to authorities, similar accidents happen frequently. If a car stalls on the highway, police recommend drivers call 911 and a patrol car will come out and make the area safe to change a tire or make any other repairs to the vehicle. Police say most drivers are not aware they can get help.