ST. LOUIS, MO - The owner of a car walked out from their morning work out to find their parked car in a massive sinkhole.

Saint Louis city officials say the water main under the road had been broken for awhile before the road collapsed.

The Triad's seen several sinkholes within the last few years. In March, NCDOT workers fixed this 10 by 12 feet sinkhole in Elkin. In Winston-Salem, a sinkhole closed Hanes Mall Boulevard in 2016.

2 Wants to Know did some digging into how sinkholes form.

According to USGS, most sinkholes occur when things like sand or clay are carried by running water into the cavity underground. As water and sand make their way down, the layer that covers them forms an arch, which then pushes the cavity up until it reaches the road and causes a sinkhole.

Most sinkhole damage happens in Florida, Texas, Missouri, Kentucky and Pennsylvania.