The boys, all aged between 15 and 16, died when an overloaded car smashed into a power pole with such force the car was split in two.
The group have been named by police as Javarney Drummond, Andrew Goodger, Niko Hill, Joseff McCarthy, and Jack Wallace.
They were travelling in an overloaded car on the northern edge of Timaru when it crashed into a power pole on Saturday night - splitting in half and hurling debris down the road.
The driver, a 19-year-old, was the sole survivor. The five victims were aged between 15 and 16.
Area Inspector Dave Gaskin said police were still piecing together what happened and very little could be gleaned from the car itself because it was extensively damaged.
"I haven't seen too many crashes in my time where there's been total destruction of a car," he said.
"I would expect it was travelling in excess of the speed limit. The car was split in half by the pole and the part the driver was sitting in, the front quarter of the car, was 38 or 40 metres up the road from the pole.
"So it's travelled a considerable distance."
A message is going around urging people to come to a car event in memory of the boys on Friday.
They are being encouraged to "bring their loudest cars" to show how much the boys will be missed.
Timaru Boys' High School rector Dave Thorp urged students against attending.
He asked parents to discourage their sons from attending, citing serious safety concerns.
Gaskin said it was understandable the community wanted to farewell the boys but asked that commemorations be safe and within the law.
He urged anyone who saw the car - a blue Nissan Bluebird - before the accident, to get in touch.
Gaskin said it had been a tough few days for everyone, including police.
"Advising people that a loved one has being killed in a crash, or for any other reason, is the worst job you can possibly imagine anyone would have to do," he said.
"You walk into someone's life and destroy it pretty clearly. We certainly do a lot of training on it, our staff are very good at looking after them and we've got great support from victim support.
"But that initial contact was always difficult."
Gaskin said police were focused on road safety but he felt for parents trying to teach their children how dangerous it was behind the wheel.
"It's very difficult to stop people doing silly things when they want to do silly things," he said.
"Trying to remove that risk, it's very difficult. I totally understand the difficulties parents face these days. You've got to teach them early in their lives and hopefully they understand when they get older."
Gaskin said the 19-year-old driver was in a serious but stable condition in Timaru Hospital and had not yet been spoken to by police.
