Federal investigators Monday were looking into reports that some sections of a southwest Washington railroad track had given trains a rough ride in the days before a four-car passenger train derailed.
A federal railroad inspector reported rough riding March 23 on tracks about 250 feet from the accident site.
At the time, Burlington Northern Santa Fe Railway Co., which owns and operates the tracks, acknowledged receiving the report and said it would respond, but did no other follow-up.
There had been four recent reports of rough riding on the track. The locomotive on a four-car Amtrak passenger train carrying 107 passengers and eight crew members jumped the tracks at 60 mph Sunday morning, about 40 miles east of Vancouver, Washington.
The accident left the cars partially upright, leaning at a 45-degree angle against an embankment alongside the track.
Authorities said 26 people were treated for injuries, none of them life-threatening.
After the accident, those who could travel were loaded onto school buses and taken to Vancouver and Portland, Oregon.
The cause of the railroad derailment "could be anything," according to an official, suggesting there could have been an alignment problem, a warp, or a slight drop in elevation on one side of the tracks.