Firefighters extinguished a massive fire burning west of downtown Phoenix that temporarily shut down Interstate 10 Wednesday night. The second-alarm fire was burning at Burlington Northern Santa Fe Railway near 19th Avenue and McDowell Road on May 4, officials said. First responders discovered a large pile of railroad ties fully engulfed in flames. The situation was treated as a hazmat incident because of the unknown contents of the nearby railcars. The Arizona Dept. of Public Safety shut down I-10 at 7th Avenue for several hours due to the direction of the smoke and the proximity of the fire. "Fire control was achieved approximately two hours after the initial dispatch," officials said in a statement. "Crews will remain on the scene throughout the night to extinguish all remaining hotspots."