Newtown High School has been placed on lockdown following an attack on the school.
Parents and students are being advised to seek shelter in their homes in a large area of Newtown after the incident on Thursday night.
The lockdown has been lifted following the incident.
The area is being patrolled by the Garda Siochana and Gardaí.
The incident at Lee High has been referred to the Criminal Investigation Bureau (CIB) as a ‘massacre’ as gardaí are investigating the attack and are looking for witnesses.
The attack happened in the area of Park Avenue and Euston Street and injured three children.
The injured children are being treated in hospital.
Three men have been arrested and are currently in custody.
The other two men have not been arrested.
The Garda Commissioner has announced a Garda Emergency Response Team will be deployed to the area as part of an ongoing investigation into the incident at the school on Thursday evening.
The school has been put on lockdown.
Garda officers will remain at the site for the duration of the lockdown.
Gardaí have confirmed that a car, possibly a Ford Focus, was used in the attack on Lee High.
Gardai have also appealed for witnesses to come forward.
Anyone with information is asked to contact Crimestoppers on 1800 333 000 or the Gardai Criminal Intelligence Unit on 0800 666 111.