Emergency services have been called to a shed fire at the side of the highway in Waikouaiti tonight.
A Fire and Emergency New Zealand spokesman said crews from Palmerston and Waikouati stations were notified of the blaze near State Highway 1 about 7.35pm.
Upon arrival, they found the shed well alight.
Some cars were believed to be involved in the blaze, the spokesman said.
A police spokeswoman said about 8.30pm that officers were helping with traffic control and the south-bound lane had been blocked off.