Sparks were flying off a freight train moments before a wagon derailed, partially blocking State Highway 1 in Clinton last night, a witness says.
A police spokeswoman said a rear wagon derailed about 7.30pm between Gorge Rd and Nelson St.
Dunedin man Mike Owen said he was travelling to the city from Invercargill, when he heard the roar of the train.
"The train was going past and it got louder and louder and I thought 'this is odd' and then I saw sparks coming off it high in the air and then part of it fell off the track."
There were about five cars on the road when the incident occurred and it was fortunate the wagon did not derail near traffic, he said.