Four garages caught alight in the rear carport of a unit complex on Discovery Street, and emergency services responded at about 9.20pm.

While no units were affected, there was a ute inside one of the garages which was also damaged.

Emergency services gave a preliminary estimate of the damage bill at $50,000.

Police are now investigating after a survey of the scene found it to be suspicious.

Investigators believe it was deliberately lit.

Police are seeking witnesses, and asking them to contact Crime Stoppers on 1800 333 000 or use the Crime Stoppers website at act.crimestoppers.com.au.