Cannabis oil is suspected of causing one of two house fires in Westport last night.
Fire investigators and police are investigating.
The first fire, at 5.30pm, gutted a house in lower Russell Street. The second, at 10.30pm, damaged the kitchen of an Orowaiti Rd property.
Sergeant Malcolm Lamont said the fire call to Orowaiti Rd followed an explosion while cannabis oil was being cooked in the kitchen.
A 61-year-old Westport man had been arrested and charged with manufacturing cannabis oil and possession of cannabis, he said.
The man was to appear in Greymouth District Court this morning.
Mr Lamont said investigations were continuing.
Fire chief Alan Kennedy described the fire at Orowaiti Road as a "minor kitchen fire". It took firefighters about 45 minutes to deal with it.
He said the occupants of the unit - one of three adjoining flats - were out of the property by the time firefighters arrived.
The earlier fire at Russell Street was a much bigger blaze and had taken over three hours to extinguish, Mr Kennedy said.
Three fire appliances and 20 firefighters attended.
"We had to fight it externally at the start because it was too well involved to go inside, then once we got the flames knocked down we entered the house through the front door."
It took about three-and-a-half hours to quell the blaze, he said.
The 111 call was made by a person in the house who noticed the fire. He had escaped the house when firefighters arrived.
Both Westport fire appliances responded and backup was called in from Waimangaroa and Granity brigades.