The emergency apparently began after a car caught fire about 4 a.m. and flames spread to the junkyard.
The London Fire Brigade set up a temporary hazard zone in case the gas cylinders started exploding.
Eight fire engines and 40 firefighters worked to extinguish the fire, but officials said the road could be closed until noon Saturday.
The fire could interrupt travel plans for many people who planned to take advantage of two four-day holiday weekends, including Easter April 24 and a royal wedding April 29. Prince William and Kate Middleton will be married at Westminster Abbey.
Written by United Press International