The Minnesota State Patrol says a fatal crash near Mankato Monday was caused by a hit-and-run driver.

Twenty-year-old Jaylynn Williams, of Mankato, was killed and her boyfriend, Dennis Egge, was injured when their vehicle left Highway 60 west of Lake Crystal about 4:30 p.m. Monday. Egge tells the Star Tribune Williams waved at the other driver “just to be nice,” but he flipped them off. He says the two vehicles touched slightly before the SUV he was driving veered off the road.

The two were returning from a trip to Nebraska and were minutes away from Mankato when the crash occurred.

The patrol has turned to social media to find the driver of the other vehicle, which was captured on a police dashcam around the time of the crash.