Fire crews trained in urban search and rescue slid a trapped woman to safety Wednesday morning, nearly four hours after she fell into a narrow gap between the exterior walls of two downtown Portland buildings.

The unidentified woman emerged, still wearing her eyeglasses and a short sleeved aqua T-shirt, around 7:30 a.m.

, when Portland Fire Bureau crews responded to the garage of the

in the 1200-block of Southwest Columbia Street. Witnesses reported hearing a woman scream for help, her calls for help seeming to point rescuers to the cinder block wall of the Commons' street-level parking garage.

Her cries woke up Joseph Ryan, who lives in a fourth floor unit of the Commons, a low-income apartment building adjacent to Interstate 405.

"I heard her voice: help me, help me, help me, I'm slipping," Ryan recalled later.

"I thought she was being attacked. The terror in her voice -- I've never heard anything like that before. It was pretty intense."

Crews determined the woman was positioned near the base of a wall, trapped in barely a foot of space between the 20 foot tall concrete block garage wall and the even taller, unreinforced masonry wall of New Avenues for Youth, the building next door.

The Portland Fire Bureau's Lt. Rich Chatman said crews worked quickly to assess how to reach the woman, who remained alert and feisty during her ordeal.

"We had to look at several different options: whether to try to hoist her out or cut into the wall. We decided to go through the wall," said Chatman, who ultimately pulled the woman to safety.

After threading in hoses to pump warm air into the wall and remove excess carbon dioxide, firefighters soaked the wall with water and began poking and drilling holes through the concrete.

Sparks flew as crews used industrial saws to link the holes to create squares on either side of the woman, who perched on her heels on a thin outcropping from the masonry wall, four feet from the ground, facing the garage wall.

They removed two 2 by 2 foot windows that let rescuers get a better look at the woman. Crews passed her a blanket and water and harnessed her in so she wouldn't slide further into the narrow space. Her husband was brought to the wall to offer words of support.

Then firefighters sprayed a soapy substance inside the walls and on her, to reduce friction when they tried to pull her out.

Crews expanded the window to her left into a door-sized opening, drilling in an eye bolt and using a cable to pull the cinder block chunk free. The plan called for deploying airbags to widen the area by even a quarter of an inch, Chatman said.

"It was so tight, we needed every bit of help," he said.

But the woman was ready to come out. She helped push the concrete away, and then, with a twist of her body, followed it out of the wall.

"She yelled, 'I'm coming out!'" said Chatman, a 36-year-old firefighter on the job 15 years. Crouched in the opening, Chatman helped pull the woman free.

More than two dozen firefighters took part in the rescue, many of them, like Chatman, members of the urban search and rescue team that trains frequently for 'high-risk, low use' efforts like the one Wednesday.

It was his last day on the job. On Thursday, Chatman begins a new assignment as a spokesman for the fire bureau.

Still splattered with damp grey concrete dust, he spent the hour after the rescue getting good experience for the job, granting interviews to television, radio and newspaper reporters.

It remained unclear how the woman fell into the wall, which could only be reached two ways: from an adjacent wall -- barely the width of a hand -- that forms the back of the garage, and from the roof of the neighboring building.

Lt. Damon Simmons, a spokesman for Portland Fire, said investigators would determine how the incident happened -- and how to prevent such an occurrence in the future.

Meanwhile, the woman, looking barely worse for the wear after her ordeal sliding between two walls like a pachinko ball, was wrapped in a white sheet and placed on a gurney.

She hugged fire fighters as she was rolled to an ambulance, enroute to

, where she remains Wednesday afternoon. She requested that hospital officials not release any information about her condition or identity.

If the story sounds vaguely familiar, it could be because crews near Brown University in Providence, R.I., pulled off a similar rescue in November, when firefighters cut through a wall after a woman got trapped between two buildings.

Initially, authorities believed the woman fell through a narrow opening at the top of one of the walls.

.

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-- Reporters Noelle Crombie and Lynne Terry contributed to this report.