The deaths in the city of Lahaina, the island's main tourist destination, came as strong winds from a distant hurricane fanned the flames, the BBC reported.
The fire is one of several ongoing blazes that have burnt entire neighbourhoods to the ground.
Thousands of people have been forced to evacuate their homes and a state of emergency has been declared.
A huge search and rescue operation is under way, with some people still unaccounted for.
"We barely made it out in time," Kamuela Kawaakoa, who fled to an evacuation shelter on Tuesday with his partner and six-year-old son, told the Associated Press.
"It was so hard to sit there and just watch my town burn to ashes and not be able to do anything," he said. "I was helpless."
Five evacuation shelters have been opened on Maui and officials earlier said they were "overrun" with people. The island is a popular tourist destination and visitors have been urged to stay away.
"This is not a safe place to be," Hawaii Lt Governor Sylvia Luke told reporters. "We have resources that are being taxed."
Firefighters are still battling active fires, with helicopters dropping water on the blazes from above.
The western side of the island, which is the second largest of the Hawaiian archipelago, was almost cut off entirely with only one main road open.
"As the firefighting efforts continue, 36 total fatalities have been discovered today amid the active Lahaina fire," the Maui county government said in a statement late on Wednesday.
Dozens of people have been injured since the fires began burning on Tuesday and hospitals on the island are treating patients for burns and smoke inhalation.
MNA/PR