Police are investigating a suspicious fire at a house in Cannons Creek, Porirua, on Saturday 7 April 2018.
At about 4am, Fire and Emergency NZ responded to a house fire at 9 Northumberland Street.
The fire caused extensive damage to the property and was determined by investigators to have been the result of arson.
Three adults and one child were inside the house and asleep at the time the fire was started.
"Fortunately they were woken by smoke alarms and able to evacuate their home," says a police spokesperson.
"Police are looking to speak with any witnesses who may have seen anything suspicious in the area around this time.
"We are particularly interested in speaking to a male who was seen walking in the area at the time of the fire."
He has been described as Maori or Pacific Islander in his late 20s to early 30s.
He was wearing black jeans and a black and yellow singlet with the number 7 on his back and carrying a black backpack.
Anyone who may have seen something or has information relating to the fire is asked to contact Constable Lizzie Campbell at Porirua Police Station on (04) 238 1400 or report anonymously via Crimestoppers on 0800 555 111.