Serious crash closes SH1 in North Canterbury

State Highway 1 is closed after a serious crash at Leithfield in North Canterbury this afternoon. 

Police said they were alerted to the two-vehicle crash at 4.20pm. 

"Initial indications are that there are serious injuries," a police spokesperson said. 

It is unknown how many were injured in the crash. 

Diversions are in place and motorists are advised to avoid the area.