Three teenagers have been arrested following a fire at the old planning offices on South Hill yesterday afternoon (3 Jan).
Emergency services were called to the scene at 2.08pm, with police and Jersey Fire and Rescue attending. An ambulance was put on standby.
25 firefighters were tackling the flames at the peak of the incident, with four fire engines, an incident command vehicle and fire duty manager also on scene.
JFRS say that while the fire was extinguished it was 'difficult to access'.
The fire service stayed at the building, dampening down flames until after midnight, with roads remaining closed for that time too.
No injuries have been reported and all roads have since reopened.
Paper was set alight in Pier Road toilets as well, and police are linking it to their investigation.

Gas price increase for Guernsey and Jersey
No injuries after car and outbuilding fire in Grouville
Nursery to move into Les Creux Pavilion
Jersey to get another royal visit
Emergency services to test response to terror attack
Final States meeting for current crop of politicians
Jersey pupils travel to UK finals of F1 STEM racing
Islanders coming from Kent universities to contact Public Health