"Under it, it looked like it was just a faucet running," Flack told the television station. "It was all liquid coming out from the bottom of it."
A nurse performed first aid as emergency software inside Flack's car automatically called 911, WCCO reported.
"The ground just becomes soft as we start getting more rain," Minnesota State Patrol officer John Baker told KARE. "And gravity takes places and boulders start falling, trees start falling."