The incident occurred near New Odlabari station when the bison which was crossing the track and was hit by the Howrah-bound Kanchan-Kanya Express last night with visibility being affected due to fog, sources said.
Railway officials said, train services were affected for half-an-hour and resumed after the tracks were cleared.
Three full-grown elephants were killed yesterday at Rajabhatkhaoa in the Buxa forest range when they were hit by the Guwahati-Ranchi Express in the same district.
Forest and railway officials rushed to the spot and services, which were disrupted, could be resumed only after clearing the tracks, sources said.
Earlier, ten elephants had been killed after they were mowed down by a train in October 2010 near Banarhat tea estate in the Moraghat forest range.