SACRAMENTO (CBS13) – A mysterious oil spill led to a hazmat situation outside a Sacramento County convenience store overnight.

The spill was first reported around midnight.  A customer walked into the 7-11 store on Antelope Road at Tupelo telling the clerk there was a lot of oil in the parking lot.

Fire fighters estimate about 20 gallons of oil leaked or spilled into the lot but could not find a source.

Hazmat crews sectioned off the spill and put down an absorbent material to get it cleaned up.