Police have carried out a controlled explosion on a chemical substance at a south Belfast school.
Pupils and staff at Wellington College were evacuated after an incident was reported to emergency services shortly before noon on Wednesday.
Police closed off part of the Carolan Road to motorists as firefighters arrived at the scene.
It emerged in an email from the school principal, David Castles, to parents that the incident was sparked by a chemical used in experiments by A-Level pupils.
The email explained how it was discovered that the composition of the chemical had changed and “having taken advice from relevant authorities, all necessary steps were taken to deal with the issues quickly and safely”.
A PSNI spokesperson said: “A controlled explosion was carried out on the substance, which has been removed.”
In his email the principal praised pupils “on their conduct during the extended period of evacuation”.
He added: “I would also wish to thank staff who took all possible steps to ensure the wellbeing of students throughout this time.”
A spokesperson for the NI Fire and Rescue Service said the incident was resolved by 2.22pm.