The head of the school where four teenage former pupils were killed in a horrific crash on Friday said they had had a life of potential ahead of them. 

Simon Coe, rector of Southland Boys' High School, said the accident is a difficult time for the Bluff, Invercargill and SBHS communities. 

"Our thoughts are with the grieving families and we have reached out to them. 

"We are saddened by the loss of four young men who had a life of potential ahead of them," Coe said. 

He said the staff team at the school will be available for affected whanau and friends over the coming times. 

The crash between a concrete truck and a ute took place just before 4pm on Friday. Photo / George Heard 

Police have named the four teens who died as Konnor Steele, 16, Indaka Rouse, 16, Kyah Kennedy, 16, all from Bluff and O Maruhuatau Otuwhare Tawhai, 17, from Invercargill. 

Emergency services converged on Queens Drive after the crash and were "shook" to find the four teens dead in the cab of the ute. 

Tributes and photos have been posted and shared widely of the boys, whose deaths have shaken the Invercargill and Bluff communities. 

"I'm sitting here writing this with tears in my eyes. Gone but not forgotten, taken too soon along with everyone else," said one friend. 

"Frvr 16." 

The family of another boy spoke of his death on Facebook. 

His brother posted a photograph of them together, captioned: "Fly high little bro, I love you so much." 

Their mother then wrote, "rest in love baby boy". 

Another relative said: "There are no words to express how I'm feeling. I'm absolutely heartbroken, I will miss you so much mate. Love you forever." 

And the sister of another victim posted the last photo she took with him. 

"Fly high little brother. Literally no words right now. Just lost," she wrote. 

They were sons, moko, brothers, best mates. 

They were loved. And on Friday, in an instant, four Southland teenagers were lost forever. 

Emergency services attend the scene of a crash on Queens Drive, Invercargill, in which four teenage boys were killed on Friday. Photo / Ben Tomsett, ODT 

Police are still working to piece together how the Ford ute they were travelling in collided head-on with a concrete truck on an inner-city street in Invercargill just before 4pm on Friday. 

Footage of the immediate aftermath of the crash seen by the Herald showed members of the public, including an off-duty surgeon and nurse, frantically clambering onto the wreckage to try to help. 

The Herald has contacted family members but they were not ready to speak publicly. 

The driver of the concrete truck also declined to comment. 

He was not injured in the crash and was doing "okay" yesterday. 

The Herald understands he spent time on his own at the scene of the crash Saturday afternoon after police lifted the cordon and reopened the road. 

The after-impact footage shows the driver screaming and jumping out of the cab window before walking to the side of the road, incredibly distressed. 

- by Bernard Orsman, NZ Herald