Multiple calls came in to emergency services about the incident at around 9.50am with firefighters, police officers and paramedics all attending.
On arrival, crews discovered that the blaze had only affected scaffolding and plastic sheeting around the exterior of the building and, visually, may have initially appeared more significant.
Around 280 apartments, a restaurant and retail area are being built at the site by French construction company Groupe Legendre on behalf of the Jersey Development Company.
The Health and Safety Inspectorate, which investigate workplace incidents, are at the scene.
Full story: See Tuesday's JEP.