Investigators are trying to find out who may have set thousands of railway ties on fire North of Pueblo. Firefighters were called late Saturday night after the fires were spotted near mile marker 108 and I-25. Railroad ties were burning in two separate locations and the Pueblo County Sheriff’s office says more than ten-thousand of them were set on fire. B-N-S-F Railway is leading the investigation into the fires, which are thought to have been deliberately set.