Cattle wandering on railway lines were struck by a freight train on the Kaipara Flats overnight.
KiwiRail general manager operations Upper North Island Henare Clarke said some were of the herd of 20 were injured and had to be euthanised.
The cattle were hit about 9pm.
"This a timely reminder of the need to keep land well-fenced to prevent incidents like this happening," Clarke said.
The train was undamaged, and the line re-opened at 1am.
