One person has been seriously injured when a car crashed into a barrier on Auckland's Northern Motorway.

The incident has caused heavy congestion right before rush hour.

Emergency services attended a crash involving one vehicle that crashed into a barrier on the Northern Motorway, southbound near Tristram Ave just after 4pm.

One person has been taken to hospital in a serious condition, a police spokesperson said.

The New Zealand Transport Agency said one lane had been blocked as a result of the crash.

Traffic is heavy on the southbound lane as traffic congests, and also heavy on the northbound lane between Onewa Rd and Tristram Ave due to rubbernecking.