Senior Station Officer Lindsay Rae, of the Dunedin Central station, said firefighters were called to three suspected arsons in South Dunedin, which took place from just before 8.30pm to just before 9pm.
They were first called to a skip fire in Grosvenor St and, while that was going, they were called to a fire which caused ''considerable damage'' to CT Electrical in Lorne St.
However, it could have been a lot worse.
''It could have been catastrophic because it was under an overhanging building and had we not arrived when we did, the building would have been well alight in no time at all.''
While two fire appliances were putting out the fire at CT Electrical, a third was called to a fire 200m away in Broughton St.
A Fire Service spokesman said there was no significant damage in the other two blazes.
Mr Rae criticised the actions of those who lit the fires, saying he was disappointed with their ''total irresponsibility'' and disregard for property.
Acting Senior Sergeant Ben Butterfield, of the Southern District command centre, said the fires were being treated as suspicious.
Two youths had been seen running down Lorne St after one of the fires and police were keen to hear from anyone who had seen suspicious activity in the area.
