Officials with Union Pacific says its findings are preliminary.
Raquel Espinoza is a spokeswoman with the railroad.
“It appears a fastener that connects the rail tie with the rail could’ve contributed to the cause, but we are still looking at different pieces of evidence,” said Espinoza.
Some industry experts say they’re skeptical that a fastener alone could be the cause of a derailment that size.
A total of 16 cars derailed in the incident spilling 42,000 gallons of crude oil.
Union Pacific has made repairs to the tracks and resumed train service.
Many of the derailed cars still contain crude oil. But officials with Union Pacific and the Washington Department of Ecology say it’s safe.
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