Why Is Oil Seeping From Ground in Wilmington?

Wilmington, California why is the water and oil seeping from the ground?  

A broken pipe caused crude oil to seep onto the streets of Wilmington overnight Tuesday, officials said.

Hazmat units with the Los Angeles County Fire Department responded to reports of oil flowing through cracks in the asphalt on the 1200 north block of Neptune Avenue at 7:00 p.m. Monday night, according to fire officials.

CBS2's Joy Benedict reports neighbors started seeing liquid Monday afternoon and at first believed it to be water. They later contacted the fire department after realizing the liquid was, in fact, crude oil.

"You never expect something to start bubbling out of the concrete," resident Naomi Payan said.

Once the oil flow on the street was stopped, various county health and hazmat services were dispatched to the location, along with crews to repair the broken pipe and cap the source of the leak, officials said.