The fire began at the rear of the building and spread to two stand-alone storage sheds and the annex running along the length of the building, which contained storerooms and toilet facilities for each shop, Johnny Chapman, of Alexandra, said yesterday.
But a fire wall between the annex and the main retail areas and the quick arrival of firefighters stopped the flames from spreading further, he said.
Constable Graeme King, of Invercargill, said at the scene the fire ''certainly looked suspicious'' and was being treated as arson. Police were also investigating another suspected arson about the same time when a car was set alight in the nearby suburb of Gladstone.
All the shops - a dairy, takeaway shop, a hairdresser's, bridal shop and the Invercargill office of the New Zealand Educational Institute (NZEI) teachers' union - sustained smoke damage.
Smuts and discolouration could be seen on the white and cream dresses at 4 Ever After Bridal.
Owner Sarah McBurney said she did not know whether any gowns had been damaged beyond repair as she and other tenants had not yet been allowed back into the building. It was the wedding season and brides were already ringing her to ask whether their dresses had been damaged, she said.
Takeaway shop owner Bruce Kwong said he was grateful the fire had been put out quickly.
''Fifteen minutes later and everything would have been gone.''
He said he had been told the fire began in or beside the storage shed behind his shop in which he kept stock and equipment. He was ''very disgusted'' someone would set fire to someone else's property.
NZEI southern lead organiser Dayle Belcher said it did not appear the union office had been seriously damaged. People living in flats next door to the shops were evacuated soon after the fire broke out.
Mr Chapman and his wife Pamela, who live in Alexandra, have owned the insured shop building since 1994. Mr Chapman said he hoped rebuilding would begin within a few days.
''The most important thing is that my tenants can get their businesses going again.''
