Police said several cattle died and others were put down after the crash near Peak Hill, about 45 minutes south-west of Dubbo, about 5.10pm yesterday.
Police said one of the occupants of one of the cars died at the scene, about 10 kilometres north of the historic gold mining town, while the other six were taken to hospitals in Dubbo and Parkes with non-life-threatening injuries.
One of the cars was towing a horse float but a police spokesman said the horses were all believed to be alive and well.
He said about 10 cattle died in the crash or were euthanised.
Others appeared to have escaped and were seen roaming around on and near the road.
The Newell Highway remained closed early this morning about 10 kilometres north of O’Leary’s Lane as authorities cleaned up and police began their investigations.
“The roadway is expected to remain a crime scene for a considerable amount of time and motorists are urged to avoid the area,” police said, in a statement issued about 9.30pm yesterday.