The couple were on the road following opening newly renovated basketball courts in Moss Point, the town where the professional basketball player went to high school.
In photos obtained by The Sun, the pair can be seen standing outside of their vehicle in the road while caught in a traffic jam.
The Keeping Up With The Kardashians star, 25, appeared to be horrified and very emotional at what she witnessed, standing beside Booker, 24, with her hand clapped over her mouth as they both stared out towards the wreckage.
According to local authorities, the accident took place shortly before 1pm near Biloxi Bay, when a driver of a truck with a tractor hitched to the back began to spin wildly out of control while crossing a drawbridge grate.
The driver side then slammed into the west-side bridge barrier, causing the man to be tragically thrown from the vehicle and into the bay.
The unidentified man was found deceased in the water around 2:30 p.m.
Neither Jenner nor Booker were personally involved in the accident. They were caught in a significant amount of traffic caused when the southbound lanes of the freeway they were on were closed so that authorities and medical personnel could safely look for the driver.
Though there were no other reported deaths in the accident, a passenger in the truck was injured in the crash. They are currently in the hospital and in stable condition.
As OK! previously reported, the couple have been linked romantically all the way back to early 2020, but the notoriously private KUWTK star chose not to go Instagram official with the romance until Valentine's Day 2021.
Since then, her social media has been filled with sweet snaps of herself and the 24-year-old Phoenix Suns player, who recently helped lead their team to Olympic victory against France.