Emergency services, including four fire appliances, were called to the address after a neighbour reported the blaze just before 10.30pm.
Fire Service investigator Cathy Trevathan visited the scene yesterday, but would not comment on her findings.
She referred all comment to police.
Senior Sergeant Craig Dinnissen said the CIB was investigating.
He would not comment further, other than to say ‘‘inquiries are ongoing''.
Neighbour Amy Mckay said she was alerted to the blaze when she heard sirens.
Another neighbour told her to get out of her house as the blaze was so close to her property.
‘‘It moved very quickly,'' she said.
‘‘It goes straight up.''
She had heard banging as the fire blew out windows, but did not realise the cause of the noise until she heard the sirens.
By the time she got to the street, fire was ‘‘coming out the windows''.
