Firebug targets units, bins, trees and a car in Wollongong, Coniston

The fires started around 1am on Thursday, October 12, with residents' lives put at risk when fires erupted in two separate Wollongong unit blocks.

A mattress was set on fire in the common area of a Cliff Road unit, and items stored in a garage of a Church Street unit were torched. A built-in sprinkler system helped douse the garage fire until firefighters arrived on scene.

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Trees, bins and at least one car was set on fire, with Staff and Church streets in Wollongong among the locations of the arsonist's attacks.

Nobody was injured in any of the fires.

"It went for a good couple of hours," Fire and Rescue NSW Wollongong Station Officer Matthew Gregory said of the spate of fires.

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So many fires occurred within such a short time period that firefighters from other stations were brought into the area to help extinguish them.

FRNSW Inspector Andrew Barber said the firebug focused on "easy targets" across the suburbs.

"He's going to have been caught on CCTV somewhere," he said.

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Due to the large number of fires and widespread nature of the crime scenes, Wollongong Police District Chief Inspector Steve Worthington said their investigation is still in its infancy.

"If anyone has any information or knowledge about the fires last night contact Crime Stoppers on 1800 333 000.

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