Sergeant Barbara Goodwin said initial investigations showed a northbound truck had collided with a southbound vehicle which had stopped while children were using the crossing.
Investigations into the crash were continuing.
She asked for anyone who saw the crash to contact Constable Anton Keeve at Whangārei Police on 430 4500.
The road was blocked for about two hours while the investigation took place and the road was cleared. Traffic in both directions was diverted up Otaika Rd behind the shops.
A man, who did not want to be named, said he lives at the nearby holiday park and came out to the shops after he heard "a big bang".
"We've had that many crashes, you know what they sound like."
The area of SH1 near the Otaika shops has seen several crashes in recent years.
In December 2016, a 10-year-old boy was hit and thrown about 12m while using the crossing.