Police homicide investigators are trying to determine what led to the death of a 22-year-old woman who climbed into an air duct on the roof of the Ala Moana Center food court Saturday afternoon. She was in extremely critical condition when her body was freed from a range hood above one of the restaurants nearly 2 1/2 hours later.

Police Lt. Bill Kato, who heads the homicide detail, said the woman entered an air vent on the food court roof at about 1:30 p.m. or 2 p.m. after an Ala Moana Center security worker approached her.

"She was sitting on the vent and the security worker asked her what she was doing," Kato said. "Our information is that she told the security person that her job was to clean the vents."

Kato said investigators planned to meet with the shopping center management yesterday afternoon to verify the woman's vent-cleaning story and answer other questions about how she got onto the roof and into the air duct.

City Emergency Medical Services Assistant Chief Donnie Gates said dispatch logs show paramedics arrived at the food court about 3 p.m. Saturday and left for The Queen's Medical Center about 5:10 p.m. with the woman.

The patient was pronounced dead at Queen's, Gates said.

An autopsy was performed Tuesday, but determination of cause of death awaits test results, officials said.

Kato said police investigators were not called to the scene on Saturday and are trying to piece together what happened based on reports filed by firefighters, city paramedics, mall security workers and others.

"Based on the reports we've seen so far, she was reported to be in stable condition — at least initially," after becoming stuck in the air duct, Kato said. "People were talking to her, and she was responding and was said to be in stable condition."

But at some point, while Fire Department rescue workers were trying to free her from the range hood above the grill at Little Cafe Siam, the woman "went unresponsive," Kato said.

Fire Capt. Kenison Tejada said it took rescue workers 40 to 50 minutes to rescue the woman after they arrived at the Food Court.

He said rescuers first had to cut through the thick steel of the range hood, which was designed to withstand cooking explosions, and then had to use hydraulic spreaders to free the woman.

Rescue efforts were hampered somewhat because the woman's body was pressed against the top of the range hood.

"She was communicating with the rescue workers most of the time but began to get very anxious toward the end and then became unresponsive," Tejada said.

Paramedics were able to monitor the woman's vital signs because one of her arms was dangling though the range hood, Tejada said.

Reach David Waite at dwaite@honoluluadvertiser.com.