The National Transportation Safety Board plans to send 20 investigators to probe the derailment of an Amtrak train in Washington state that left at least six people dead and many more injured.
NTSB Board Member Bella Dinh-Zarr told reporters the "go-team" will work to determine how the incident occurred.
The derailment occurred on a section of track that was recently upgraded as part of a $181 million project, according to the Associated Press. The construction was overseen by Sound Transit, the Seattle-area public transit system, which owns the track.
An agency spokesperson told the AP extensive testing was done before the system opened Monday.