The house is occupied by a woman who has lived there for many years and a man who moved in about three months ago. The two men in the shed did not live on the property.
While another neighbour went to call 111, Ms Bartlett helped the woman from the house deal with the burned men.
Local residents there to see what caused the explosions and fire described the pair's burns as "horrific" and "a nightmare". They told the Advocate the burns were the worst injuries they had ever seen.
Ms Bartlett and others bound burned limbs with plastic wrap and tried to calm the men before Kaikohe firefighters, St John ambulances and about six carloads of police starting arriving about 8.30pm and the dying fire was brought under control.
The Northland Electricity rescue helicopter touched down at dusk and locals said the expert care of the helicopter paramedic and St John staff had kept the burned pair alive.
Stabilising the men took more than an hour. They were then loaded into the helicopter, which took off at 11.15pm to fly them to Whangarei Hospital.
The younger man was later flown to Middlemore where he remained in a stable condition.
The 49-year-old died in Whangarei Hospital at 12.20pm yesterday.
Ms Bartlett, a community support worker with first aid training, said mental health wards were filling with P [methamphetamine] users.
Commenting on police suspicions about the cause of the fire, she suggested: "It [P] is turning on people who make it."
Police said the explosion and fire were the result of an accident at a clandestine methamphetamine lab.
Head of the police investigation, Detective Inspector Kevin Burke, said officers including the police national clandestine team, two Environmental Science and Research scientists and a scene of crime officer had been at the rural property searching for evidence.
He expected the scene examination to be completed about 6pm last night.
The investigation led police to a property in Kerikeri and "items of significance" were seized, Mr Burke said.
"Police don't believe anyone else was involved,"he said.
The deceased's name would not be released until next of kin had been notified.