The man who police said confessed to starting the fire that burned an 18th-floor apartment on University Avenue on Sept. 10 waited in the burning unit to ambush anybody who tried to enter, said Scott Spallina, deputy city prosecutor.

"He grabbed two knives and stood near the doorway," Spallina said. "He said he was going to kill the firemen or kill his roommates if they tried to enter the apartment to put out the fire."

Spallina said the man exited the burning apartment because the fire eventually got too hot for him to remain inside.

An Oahu grand jury returned an indictment Tuesday charging Dustin W. Saluda with first-degree arson. The charge is a Class A felony that carries a mandatory 20-year prison term.

Saluda, 28, remains in custody unable to post $200,000 bail.

Spallina said the initial estimate of the damage caused by the fire is more than $135,000.

The two-story, three-bedroom apartment is one of 169 units of the Ala Wai Plaza’s Park Tower. Saluda was one of three people who lived in the apartment.

Saluda’s roommates saw Saluda drinking a beer and heard him say he wanted to burn the apartment before they went to work, Spallina said. After the roommates left, Saluda made a torch with a lighter and an aerosol can, which he used to set the apartment’s curtains and furniture on fire, he said.

Honolulu police said Saluda told an officer at the scene that he had started the fire. They said he also told the officer that he did it because his roommates, the Hono­lulu Police Department and the Marines had hypnotized him.