Police attended after two pupils were spotted on the roof of a Leyland school this afternoon.
The incident happened at Golden Hill Short Stay School, Earnshaw Drive.
Lancashire Police said they got the emergency call just after 1pm.
A spokesperson said: “It looks like a couple of pupils have gone up on the roof.
“We’ve gone to the scene. It’s caused a bit of concern for their welfare.
“We spoke to the children and a short time later they came down.”
Police said the pupils involved in the incident were two boys.
Golden Hill is a primary pupil referral unit (PRU).
It serves the Preston, South Ribble and Chorley districts – 154 primary schools in total.
Head Alison Collinge said: “I can confirm that an incident took place at school which was dealt with quickly and safely. I would like to reassure parents that although events like this are extremely rare in our school, they are taken very seriously as the safety and security of our pupils is paramount. It would be inappropriate for me to comment further.”