In an "unusual" case, 13 students have been taken to hospital, some for minor burns, after being exposed to sulphuric acid during a small explosion in the science laboratory at the Burgmann Anglican School.
Firefighters and ACT intensive care paramedics treated the teacher and students from the rest of the class of 22 at the school on Valley Avenue, Gungahlin, following the incident on Friday morning.
Students were looking on as a teacher conducted an experiment involving sugar and sulfuric acid inside a cabinet when the glass container holding the acid exploded.
Students were taken to the showers, as the emergency services were called.
Deputy Principal John Foulcher said the students had been taken to hospital to be treated for minor burns, which resulted from the explosion, not from the acid, and others had been transported as a precautionary measure.
ACT Ambulance Service intensive care paramedics said they took five children to Calvary Hospital and eight to Canberra Hospital. The Emergency Services Agency said any injuries were minor.
As of 4.30pm the 13 students had left both hospitals, according to an ACT Health spokeswoman.
ACT Fire and Rescue said they contained the small spill.
In a letter to parents about the incident on the school's website, Principal Steven Bowers said Work Cover had been called to investigate the accident.
"We experienced a chemical accident in a senior school science class today which has resulted in minor injuries to a number of students and a staff member," he said.
He said the school had contacted families of students who were injured.
"The families of all students who were present in the class have been contacted directly," he said.
Worksafe ACT Commissioner Mark McCabe said he had sent two inspectors to the site to collect details and evidence, and expected to receive a report early next week.
Asked whether he had seen this before, Mr McCabe said "not really, it is reasonably unique. It's pretty unusual actually".
"It may have happened elsewhere but on a much smaller scale, and a lot less significance of outcome," he said.
He said Worksafe ACT would be looking into what precautions the school had in place and how they responded.
"In this case it was sulphuric acid, which as I understand is quite dangerous and the school would have had emergency procedures which would have kicked in," Mr McCabe said.
"From what we heard today the response was pretty quick and seems to have been quite throughout but that's what our investigation will reveal."
Adding to the drama, a fire alarm sounded at the school not long after the affected students were taken away to hospital, forcing students to evacuate.
The fire brigade arrived but left shortly after as it was a false alarm.