A razor blade wrapped in duct tape was the prop that cut two students' throats during a school play last night, the head of Auckland's Saint Kentigern College says.
Ambulance services were called to the college just after 9pm, during the opening night of the school's production of Sweeney Todd.
Two 16-year-old cast members suffered what were initially described as neck injuries half way through the second act of the opening night.
The two students were taken from the Pakuranga school grounds to Auckland Hospital. One was seriously injured and another had moderate injuries.
They are both now in a stable condition.
The college's head, Steve Cole, said in hindsight, the prop used could have been plastic but he was satisfied they took every precaution necessary.
He said the razor blade had been worn down and wrapped in materials including duct tape.
"They haven't used that prop all the time, but the play has been rehearsed, doing scenes 40-50 times, and often with that prop, sometimes not, but the last six or seven dress rehearsals used that exact prop."
The school is speaking with police and WorkSafe is also investigating.
A cast meeting is being held this afternoon to decide if the show will go on, and if so, what they'll do differently to prevent it from happening again.
Tonight's Sweeney Todd performance has been postponed.
Investigations under way
In a statement, WorkSafe said it was making "initial inquiries".
"The initial notification to WorkSafe advised that two boys had received neck injuries while enacting a scene in a musical production at Saint Kentigern College," the statement said.
"This information is from the initial notification to WorkSafe and may not accurately reflect the actual circumstances of the incident, which will not be clear until inspectors have completed their initial inquiries."
Mr Cole said earlier today the college was "distressed" about what had happened and its own investigation was under way.
"We are very concerned about the accident at our college musical last night and we are investigating the cause of this," he said in a statement.
"We are pleased that both boys are in a stable condition and have been talking with both their families," the statement said.
"Our priority is to support the boys and their families, along with the rest of the cast and crew.
"Productions and performance are a big part of all college life. We are distressed about what happened last night and are conducting a thorough investigation."
'Macabre, blood-soaked' play
Sweeney Todd tells the tale of a barber who kills his customers by slitting their throats. It has been widely performed on stage and adapted for the screen several times.
A post on Saint Kentigern's website explained the decision to select the grisly tale for the school musical.
"To some, the macabre, blood-soaked Sondheim classic, Sweeney Todd, may seem an odd choice for a school musical, however, once brought to the Saint Kentigern stage, there is no doubting that this is a theatre piece that raised the bar and challenged our student actors, musicians and stage crew on many levels," the post said.
"The production shows that challenging material can be delivered, and delivered well, when you have the right cast and the right creative team."
The post, published on Tuesday, also said the cast was carefully chosen.
"The cast was selected through an extensive audition process at the end of last year, with much deliberation given to casting of the lead roles."
Saint Kentigern's staff attended a meeting this morning to discuss what happened.