Approximately 50 gallons of oil was dumped in a South Crest area, authorities said.
A HazMat crew responded to the spill near Main Street and Rigel Street just before 9 a.m. Friday, according to the San Diego Fire Department.
The department handed over the incident to CalTrans and said it appeared the spill was intentional.
They later learned the oil was likely dumped about a week ago.
