KiwiRail says the death of about a dozen cattle which were hit by a train last night is a timely reminder for farmers to make sure stock are contained.
A police spokesperson said they were called to reports that a train had hit about 20 cows near Darfield just before midnight last night.
They said about 10 to 12 of the animals were euthanised at the scene.
KiwiRail South Island general manager for operations Mark Heissenbuttel said a freight train travelling from the West Coast to Christchurch had struck the wandering cattle on the Midland line.
Trains on the line were stopped while the animals were cleared.
Heissenbuttel said incidents like this were obviously catastrophic for the animals and distressing for farmers, the company's train drivers and those who needed to clear the rail line.
He said the best way to precent this from happening was for farmers to ensure their stock are contained along their boundaries with the rail corridor.
"Sadly, events like these are not unusual and last night's incident is a timely reminder of the need to keep land well-fenced and gates closed to prevent livestock getting on the tracks," he said.