Five people have been confirmed dead after Saturday night's horror crash in Timaru.
Police say the car collided with a pole shortly before 7:30pm on Saturday at the intersection of Seadown and Meadows Rds in Washdyke.
A sixth person, the driver of the car, is in Timaru Hospital with serious injuries.
"There were insufficient seats and restraints in the car for the number of people involved in the crash," police said in an update on Sunday morning.
"A full crash investigation will be carried out, however, it does appear speed was a likely factor in this crash."
National road policing manager Supt Steve Greally said the crash is devastating for the small community.
"The impact of a crash like this stretches far, and everyone in the area will be hurting.
"To have five lives lost in an instant is a terrible tragedy, and our thoughts are with their families."
Greally said it's clear not everyone in the car was wearing a seatbelt.
"This is incredibly frustrating," he said.
"Driving at excess speed for the conditions, and not being properly restrained, are two of the unsafe driving behaviours that we know contribute to death and injury on our roads, which is sadly what appears to have happened here."
Police said an investigation is continuing and work to formally identify the victims is ongoing.
