Story highlights At least two cars went off the track and over an embankment, a fire official says

Six people were injured; 98 passengers and 4 crew members were on the train

A rock slide could have cause the accident, investigators say

(CNN) An Amtrak passenger train derailed Monday near Northfield, Vermont, injuring six people, officials said. There were no fatalities.

Dana Huoppi, a spokeswoman with the Montpelier Fire Department, said at least two cars went off the track and over an embankment.

The train, the Vermonter, was headed from Vermont to Washington, D.C.

Federal investigators said the preliminary cause of the accident was a rock slide in the path of the train. A full investigation to confirm the cause is underway, officials said.

Passengers said they could feel the train jerk just before it went off the tracks, according to CNN affiliate WFFF

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