Saint Kentigern College has cancelled the rest of its Sweeney Todd production after two students suffered cuts to their throats mid-performance on Wednesday.
Two teenage boys, both 16, were taken to hospital after being hurt in the second half of the opening night show at the Pakuranga private school.
The college said an actual cut-throat razor blade was used as a prop, but that it was covered in duct tape and foam.
Sweeney Todd tells the story of a barber who murders his customers by slitting their throats. Their remains are then used as the fillings in pies.
One of the boys suffered serious wounds, and the injuries came just days after principals began to shoulder more responsibility for injuries at school, after a change to workplace regulations came into effect on Monday.
Last night's performance of Sweeney Todd was postponed by St Kentigern College because of the accident, and RNZ News understands the cast has been told the remaining two shows scheduled for tonight and tomorrow won't be going ahead.
People who purchased tickets for the cancelled shows will be fully refunded.
Principal backs health and safety process
Saint Kentigern's principal Steve Cole said ealier today he was satisfied with the health and safety procedures in place, and the prop had been used many times before in rehearsals.
"I'm very confident that the health and safety situation was strong, the staff are very professional in what they do and health and safety in the whole production has been paramount.
"It was an unfortunate, isolated incident which we're of course very disturbed about."
In its promotion of the production, the school called Sweeney Todd a "macabre, blood-soaked classic" and acknowledged it may seem an odd choice for a school musical.
But Mr Cole said it was chosen because students wanted something with which to push their skills, and a school version of the script was being performed.
"I very, very much stand by that Sweeney Todd is a demanding musical which suited this particular group of boys and girls to push their abilities, musically in particular."
He said the use of a real blade was seen as important so the production looked authentic.
School drama productions in spotlight
Equity New Zealand head Jennifer Ward-Lealand said using real weapons was rare for professional shows and schools should seek advice from professionals in cases where weapons were being used.
"Theatres are really inherently dangerous places, you're working under different lighting conditions, you're often in the dark, there are sets to negotiate and crucially, and I think potentially this happened and I wouldn't know, there's adrenaline flowing, especially on opening night," she said.
The boys' injuries come as principals have to take more responsibilities for injuries at school, under new workplace regulations, with possible penalties of a $600,000 fine or up to five years' jail.
But a lawyer familiar with the regulations said, to be held liable, a principal would have to have knowledge of a school drama having a serious risk of harm.
He added that it was also unclear if the boys' injuries would be classed as serious given they had already been released from hospital, and that liability only arises in cases of serious injury or death.
The principal of John Paul College in Rotorua, Patrick Walsh, said other schools would be taking serious note of the incident in Auckland in the wake of the new regulations.
"Any school that's had a serious accident... would cause any principal in the country to sit up and go over their dramas to ensure that they are compliant with health and safety regulations," he said.