The driver said they told him they were going to "f** that guy up".
He managed to get one of the alleged attackers in a headlock and used him as a battering ram to force the others outside.
He gave one student a cellphone to call police and instructed another to hold down the door-close button.
The driver then stood in front of the closed doors and told the teens, "do whatever you want but you're not getting on this bus".
They pulled their knives and continued to threaten him.
However, the bus driver said he had no fears that he was going to be seriously harmed.
"My faith in God got me through it," he said.
When they were unable to board, the group smashed the windows with rocks.
Nimon and Son's general manager Pete Patterson said they then tried to pull the glass out and one of them cut himself pretty badly, leaving blood spatters all over the bus.
The group fled when police arrived but were quickly found and arrested.
Police said when the teenagers were arrested three of them were carrying knives.
Hastings Boys' students on the bus called the experience "terrifying", "traumatic" and "life-threatening".
Hastings Boys' principal Rob Sturch congratulated the driver for his bravery and for keeping his students safe.
Parents, students and colleagues have all expressed their gratitude to the driver.
Mr Patterson said it was no surprise the driver did what he did because of his "intestinal fortitude".
"He's gone well beyond the call of duty, I'm not sure every driver would have done what he did."
He said if not for the driver, the situation could have been a lot worse.
"Thugs with knives boarding a school bus - if they had started slashing, that is not a headline we would want to see," Mr Patterson said.
Police yesterday confirmed two 15-year-old girls, a 12-year-old boy and 13-year-old boy were all charged with inciting violence, assault and possession of offensive weapon. A female was also charged with wilful damage by the police.
They will all appear in Hastings Youth Court next week.
A mother of two of the teenagers who allegedly threatened the bus driver was charged with threatening behaviour.
Nimon and Son's are in discussions with the Akina Activity Centre regarding the future of the two boys from the centre on the bus.
Mr Patterson said the Akina boys had been trouble in the past.
The centre caters for students struggling with other forms of secondary schooling provision and are at risk of low educational outcomes.
The Akina Activity Centre was contacted but declined to make comment.