A series of four fires lit in quick succession in the Corrimal area could have had "catastrophic" consequences, according to a NSW Fire and Rescue commander.
Five fire trucks were called to deal with four separate fires lit in a 500-metre area around Railway Street, High Street and the rail line.
The crews arrived at around 12.10pm and took an hour to get the fires lit in scrubland under control.
"It is a significant issue that the four fires were lit in such a short period of time in high winds," said Acting Superintendent Chad Wallace.
"If it wasn't for the rapid response of fire trucks the consequences could have been catastrophic."
Firefighters and police are investigating how the fires started, and Supt Wallace said children were seen in the area of the blazes.
"By tying up these fire resources to the incident, it puts the rest of the community at risk if other fires were to happen at the same time," he said.
"It also puts firefighters at risk because they are dealing with fires on several different fronts."
Supt Wallace said people with any information should contact Wollongong Police or Crime Stoppers on 1800 333 000.