Two trucks have crashed into each other, blocking State Highway 1 just south of Waikanae.
No injuries have yet been reported, but emergency services are attending the scene 500m south of Waikanae.
Police say one truck, carrying a second truck on its trailer has struck the side of a bridge over a river, then has been struck by the second truck coming from the opposite direction.
Both the north and south bound lanes of SH1 are blocked by the crash.
Police say there is considerable debris on the road and both lanes are likely to be closed for some hours.
Motorists should expect delays because there are no detours in the area.
Police suggest an alternative route to get to or from the Wellington region would be via the Akatarawa Rd, which is accessed from Elizabeth St in Waikanae, and onto Reikorangi Rd.
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