A prop which cut the necks of two Auckland private school students during a rendition of Sweeney Todd was a "razor" wrapped in duct tape and paper.
St Kentigern College head of college Stephen Cole told media this afternoon the two 16-year-old boys were wounded on stage during the second act of the musical last night.
"It was from a prop that was covered in all sorts of duct tape, foam and silver paper," he said describing the "authentic" blade which was used in the show.
"It was an unfortunate, isolated incident which we are very disturbed about."
Mr Cole said the blade had also been filed down.
He said the play about a Victorian-era murdering barber in London was "pushing the boundaries" of the students involved.
"Maybe next year we'll do something more general, but these kids need to be extended."
He added the drama teachers involved were "struggling", but were "very competent and have run numerous shows at the college".
He did not believe there would be any ramifications for the teachers.
Mr Cole said the prop had been used throughout rehearsals since January, and while some parents were initially concerned about their children performing Sweeney Todd the show went on.
He said there was no "legal situation", but WorkSafe New Zealand and police were both investigating.
"I’m very confident the health and safety situation was strong."
The two wounded students were discharged from Auckland hospital this afternoon.
The show will not go ahead as planned tonight, but is likely to resume tomorrow night.