Joel Lonzaga, 44, allegedly told police he had to do it.
"He was going to kill me and my family," he said.
Police sources said Lonzaga muttered that to arresting officers after his arrest for setting fire to his friend.
Tracy Carroll, 47, is in critical condition with second- and third-degree burns on more than 40 percent of his body.
Witnesses said the two men had been drinking together all day at Lonzaga's mom's home on Anoi Road in Kaneohe. But late in the afternoon, the two started to argue. According to police, Lonzaga poured gasoline on Carroll. Lonzaga's mom and cousin tried to break up the two, but witnesses said Lonzaga ran around them and threw a lighter at Carroll.
Flames shot in the air and Carroll ran around screaming for about 30 to 45 seconds before Lonzaga's family members were able to put out the fire.
Lonzaga was arrested for attempted murder and drug crimes, but he has not yet been charged.