Northern Ireland Fire and Rescue Service crews were called to a small fire at Larne High School this afternoon.
A spokesperson for NIFRS said: "Firefighters used a fire extinguisher and a hose reel jet to extinguish the fire.
"Children were allowed back into the assembly hall as there was no danger around 12:35pm and the incident was dealt with by 1:40pm. The cause of the fire was accidental ignition."
Posting on Twitter, Larne High School principal Dr Stephen Reid said: "Many sincere thanks to Northern Ireland Fire and Rescue Service for their prompt response to school today. School evacuated in under three minutes and everyone accounted for not longer after."