Firefighters were alerted to the blaze in Hokonui Dr (State Highway 94) shortly before 2am, a Fire and Emergency New Zealand spokeswoman said.
Two appliances attended, the crews found the building "well alight" and the fire caused substantial damage. The house was empty.
The spokeswoman confirmed the fire was at the address police attended after a firearms incident last week, and was considered suspicious.
CIB staff, scene of crime officers and photographers were at the scene yesterday assisting fire investigators.
"There will be increased patrols and support from Eastern Southland police to ensure our local communities are kept safe while these matters are being fully investigated."
Police wanted to hear from anyone who witnessed any suspicious activity in the area, particularly between 1am and 2am yesterday.
Anyone with information, who had not yet come forward, on the firearms incident last week should also contact police, she said.
■ Police 105, file number 200915/0807, Crimestoppers 0800555-111.
