Railroad crews in northern Arizona are working to repair some track near Williams after a Burlington Northern train derailed Sunday night.
Three locomotives and one car went off the tracks just west of Williams after apparently hitting a boulder.
A spokeswoman for Burlington Northern Santa Fe says there were no injuries and no hazardous materials were spilled, but the derailment remains under investigation.
Some details are not yet available, including the size of the boulder and how it got on the tracks.
The spokeswoman says the derailment blocked both tracks on the BNSF main line, but crews hope to get one track back in operation by later today.