A FIRE was deliberately started in a school yesterday (Thursday), the day after a special needs school was also set alight.
A PCSO discovered the fire in a library at the disused Martindale School in Boxted Lane, Hemel Hempstead, after hearing the fire alarm at around 4.35pm.
Officers used a small fire extinguisher kept in their police car to put out the flames.
It is believed that four offenders entered the school via an open door and set fire to books using white spirit which was found at the scene.
After the fire alarm sounded they left via a fire exit towards Boxted Road.
Four boys from Hemel Hempstead were arrested on suspicion of arson.
A 14-year-old, 13-year-old and 11-year-old have been released on police bail, and no further action has been taken against another 14-year-old.
The incident is not thought to be linked to a separate blaze on Wednesday when a suspected arsonist set fire to part of Woodfield Special Needs School in Malmes Croft.
No pupils were present at the school due to half term and an investigation was launched soon after into the incident.