Nineteen cars on a BNSF Railway train derailed about four miles west of Essex on Wednesday, bringing railroad traffic to a halt until the line could be reopened sometime today.

“The line is blocked,” BNSF spokesman Gus Melonas said Wednesday, confirming that the derailment had put the Amtrak Empire Builder in limbo along with freight train traffic.

The 115-car freight train was bound from Minneapolis, Minn., to Pasco, Wash., carrying general merchandise when the derailment occurred shortly before noon.

BNSF initially reported that the derailment was caused by a rock, mud and snow slide, but that theory was ruled out by the afternoon.

“It was not the cause of the incident,” Melonas said. “We have not determined the cause of the derailment yet.”

The derailment occurred in an area outside the avalanche-prone zone in the Middle Fork Flathead River corridor.

Flathead County Sheriff’s personnel surveyed the wreckage from a helicopter, and it did not appear to have been caused by a snow slide, Sheriff Chuck Curry said.

Curry said the concern was that hazardous materials might have been involved in derailment — but that was not the case.

One car had tumbled from the tracks and came to rest near the Middle Fork, Curry said.

Curry said there has been an elevated concern about avalanches in the corridor because most slopes have been overloaded with snow through most of the winter.

Melonas said some cars were being re-railed and others were being pushed to the side to make room for track repairs.

Equipment was brought in from Havre and Billings to assist with the efforts to reopen the track “as soon as tomorrow afternoon,” Melonas said Wednesday afternoon.

Reporter Jim Mann may be reached at 758-4407 or by e-mail at jmann@dailyinterlake.com.