The fire department reported the incident shortly after midnight Thursday. Oil was reportedly "knee-high" in some areas and the initial volume was reported at around 50,000 gallons.
After cleanup, the LAFD revised its estimate to 10,000 gallons, or about 238 barrels. Two adult women were transported to an area hospital after complaining of nausea.
The fire department said Plains All American Pipeline shut down the line remotely, though it took 45 minutes for the oil to stop flowing because of residual pressure at the pumping station.
"The cause of the oil leak was a valve malfunction," the fire department said Thursday.
LAFD used vacuum trucks and sand bags to contain the spill. Absorbents were later used to soak up the residual oil, followed by a high-pressure wash.
No oil entered the Los Angeles storm drain system.