The derailment, which affected four of the 52 cars in the cargo train, happened just after 4 a.m. by the Broadway Street end of the yards, said Gus Melonas with Burlington Northern-Santa Fe.
One car was empty, while the others carried barley and paper, Melonas said. None of the four tipped over and nothing spilled.
Crews were able to establish a detour around the derailment and Amtrak service will continue, Melonas said. Sound Transit says its commuters will be directed to bus service instead.
No one was hurt. Investigators are still looking into the cause.