The driver of the concrete truck, Rhys Wilson, was not badly injured.
A witness told the Herald another motorist narrowly avoided being hit by the ute, the driver managing to swerve out of its path seconds before the collision.
Today police said the investigation into the crash was ongoing.
"Police have spoken to a number of witnesses and would like to thank those that have come forward and spoken with us as we piece together the circumstances of the crash," said a spokeswoman.
A police cordon surrounded the crash site Saturday morning. Flowers had been left at the cordon, including one which said: "Rest in love boys". Photo / George Heard
"The truck driver has received support through Victim Support and has cooperated with police throughout the investigation.
"The investigation remains ongoing, and police would like to acknowledge the community's patience over this period as we take time to thoroughly investigate the crash, which will take some time."
The Serious Crash Unit investigation may take months as expert officers look at all factors relating to the crash from the vehicles and road to driving and weather conditions and the drivers' actions.
The case will likely also be referred to the Coroner who may hold an inquest.
Since the crash, tributes and photos have been posted and shared widely of the four boys who died.
Their deaths have shaken both the Invercargill and Bluff communities.
