The people inside the van appear to be a group of adults who have travelled from the North Island.
"This is an absolute tragedy," he said.
It appears that the van had gone through a controlled intersection at a time a fully laden truck was going past.
Two survivors from the van were taken to hospital, one in a serious condition. The truck driver was also taken to hospital with moderate injuries.
It was a terrible start to the Queen's Birthday long weekend, Gaskin said.
He urged people to be careful and take their time on the roads.
He said it appears a "moment of inattention has caused this tragedy".
Diversions are in place.
Ashburton's Mayor was devastated a tragic crash was unfolding days after severe flooding struck Mid Canterbury
Neil Brown said the sirens have been going off and there were helicopters flying over.
He says they initially thought there had been one death.
Brown said their thoughts go out to the families involved.
The area was badly affected in the Canterbury flooding earlier in the week. Gaskin added that this accident had nothing to do with the flooding.
Earlier this morning a motorcyclist died after a crash at a busy Christchurch intersection.
Emergency services were called to the scene at Riccarton Rd and Hansons Ln just before 7am.
A car was also involved in the crash.
The Serious Crash Unit was examining the scene.
Diversions are in place, with motorists asked to avoid the area.
Eight people died over the Easter holiday weekend. The official holiday period starts at 4pm today.