Federal investigators began Sunday to probe the cause of an Amtrak passenger train derailment that killed three people and injured dozens, resulting in a scramble to get those wounded to hospitals across a rural part of Montana.

Eight of the train’s 10 cars derailed about 4 p.m. local time Saturday near Joplin, nearly 200 miles north of Helena, Mont., Amtrak said in a statement, adding that an estimated 141 passengers and 17 crew members were aboard at the time.

Liberty County Sheriff Nick Erickson estimated that as many as 30 people were injured. By Sunday, five remained hospitalized in Great Falls, “all of them stabilized,” said Sarah Robbin, disaster and emergency services coordinator for Liberty County.

There was no information Sunday on what led to the derailment and local authorities had not released the names of the three people killed. The National Transportation Safety Board is investigating the derailment and said it planned a briefing on Monday.

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