A major fire is burning in thousands of wooden pallets in an industrial area in west Phoenix and has spread to nearby semi-truck trailers.

Phoenix Fire Department spokesman Mike Sandulak says the flames are tearing through a 200-yard-long stack of pallets and consuming trailers parked at a nearby freight business. An adjacent warehouse is stacked to the ceiling with new pallets and fire crews are trying to keep the flames from catching them on fire.

Sandulak says power lines are down, several explosions have been heard and firefighters are trying to keep several propane tanks from being engulfed.

More than 120 firefighters are battling the huge blaze.