Three children are among seven people seriously hurt in a crash on a main route around the Brynderwyn Hills closure.

The Cove Rd, Waipu crash was followed less than two hours later by a second at Kauri, north of Whangarei, in which one person died at the scene.

Emergency services were called to Cove Rd about 1.30pm after receiving reports of an accident believed to be a head-on collision involving two vehicles.

Three children are being transported to Starship children’s hospital in Auckland - two seriously hurt and one in a critical condition.

The remaining four people were taken to Whangārei Hospital. One patient was in a critical condition, another was seriously hurt, and the remaining two were in a moderate condition.

Rescue helicopters transport patients to hospital from the serious crash on Cove Rd, Waipu. Photo / Michael Cunningham

Two Northland Rescue Helicopters and two Westpac rescue choppers were dispatched to the scene alongside five ambulances, two rapid response vehicles and two managers. Police and the Waipu Volunteer Fire Brigade are also on site.

Cove Rd, one of the main detours recommended while the Brynderwyns are off-limits during road repairs, is closed to traffic between McLean Rd and South Rd.

Vehicles can detour through McLean Rd and South Rd to reconnect to Cove Rd.

However, NZ Transport Agency Waka Kotahi is urging motorists travelling between Whangārei and Kaiwaka to use Paparoa Oakleigh Rd. Heavy trucks and high productivity motor vehicles (HPMVs) must use State Highways 12 and 14 through Dargaville.

NZTA director regional relationships Steve Mutton said it was unknown when the road would reopen but further updates would be provided as soon as possible.

The Brynderwyns closed at midnight after a brief reopening for Easter.

”This is the last thing we want to see on our roads,” Mutton said. “I can’t encourage people enough to drive to the conditions, slow down and take extra care as you adapt to taking a different route.”

Meanwhile, police were called to the intersection of State Highway 1 and Apotu Rd at Kauri about 3.15pm after a two-vehicle crash involving a motorcycle.

SH1 is closed and diversions are in place through Saleyards Rd and Vinegar Hill Rd.

The Serious Crash Unit will conduct a scene examination and motorists are asked to avoid the area.