Story highlights A 91-year-old bus passenger dies of "traumatic impact, police chief says

The bus carried elderly and mentally disabled passengers

The train engineer told police the bus appeared to be stopped on the tracks

A collision Friday between a freight train and a bus carrying elderly and mentally disabled passengers killed a 91-year-old woman and injured several others, police in Butler County, Pennsylvania, said.

The train engineer told police the bus appeared to be stationary on the train tracks as the train approached, Evans City, Pennsylvania, Police Chief Joseph McCombs said. There were no crossing barriers or warning lights at the intersection some 29 miles north of Pittsburgh.

The woman killed was a bus passenger who died from "traumatic impact," McCombs said.

All 10 bus passengers, ranging in age from 26 to 91, and its driver were taken to area trauma centers. Only the driver had been discharged as of Friday afternoon, McCombs told CNN.