A serious crash near Maungaturoto has closed State Highway 12 and brought power lines down.

The crash happened around 4am just east of Mountain Rd, according to the NZ Transport Agency.

SH12 is closed between Brynderwyn (SH1) and Maungaturoto. The NZTA suggested motorists use SH1 to Whangarei, then use SH14 to Dargaville to avoid the incident.