PHOENIX (AP) - She's been cornered in the office elevator by perfect strangers who know only that she is a counselor. "I'm feeling a little down," they begin, and Marlene Shiple does what she can to help.

Her patients, recovering from their own traumatic experiences, relive them every day now. One was in a fire, and replays over and over again the fear of being trapped in a burning building.

"Everyone I saw mentioned it," says Shiple, a certified counselor in Phoenix. "For someone not to have some feelings about it would be totally abnormal."

"It" is the Sept. 11 terrorist attack - an event so unprecedented, so overwhelming that is has left a nation struggling with depression, anxiety, anger and outright fear.

For those already plagued by mental disorders, last week's assault may compound those problems, experts say. Panic attacks may be more severe, bouts of depression more frequent.

Yet psychiatrists and counselors agree: Most Americans are experiencing some level of emotional distress following the attacks, which thrust an entire nation into grieving.

"It's not like this is a situation we were prepared to deal with or should've been prepared to deal with," Shiple says. "It's something none of us have ever imagined."

The pain is felt far from New York and Washington and those directly involved.

"It's a national mourning," says Dr. Ken Duckworth, a psychiatrist and the medical director for the Massachusetts Department of Mental Health. "This is a loss of individuals, but it's also a loss of our collective sense of invulnerability, and that's really hard for people."

Seven in 10 Americans say they have felt depressed since the terrorist attacks, nearly half report having trouble concentrating and a third said they have had trouble sleeping, according to a poll by the Pew Research Center for the People & the Press.

Duckworth's agency established a mental health hot line and distributed an article to media outlets offering advice for those having trouble processing the events of last week. The key message: Whatever you're feeling is normal.

"There's a tremendous spectrum of human response to this, and there is no right way," Duckworth says. "Most of us will have moments of anger, moments of feeling disturbed, moments of feeling unreal. Some of us will feel a profound sense of sadness."

Phoenix retiree Denny Bayers admits riding an emotional roller coaster since the attacks. His feelings have swung from compassion for those who died to frustration with the government "for having let this happen" to worry for the future of his 1- and 2-year-old granddaughters.

"It changed the way you have to look at the world," says Bayers, 50, who's been volunteering his time answering calls at the Red Cross. Last week, a number of people were in tears when Bayers picked up the phone. He explained how they might help, and by the end of the conversation both he and the caller felt better.

"I felt very good at the end of the day - good that I did my thing," he said.

Across the country, mental health agencies are reaching out. The Arizona Psychiatric Society has compiled a list of psychiatrists and psychologists offering free services. Others have volunteered as stress counselors at the Arizona chapter of the Red Cross, fanning out at airports over the weekend to talk with passengers and airline employees.

In Connecticut, commuters shell-shocked by the attacks were greeted by crisis counselors last week as they arrived at local train stations.

Counseling centers in Oklahoma received calls from hundreds of people reliving the terror of the 1995 bombing there. "It's like a replay times tenfold of what we've been through," said Dr. R. Murali Krishna, a psychiatrist and president of Integris Mental Health in Oklahoma City.

And in Boston, where two of the hijacked airlines involved in the attacks originated, the state Department of Mental Health dispatched counselors to several state agencies to talk with workers.

"We're just trying to remind people that you are fine. This is an over-the-top event; it isn't your response that's over-the-top," says Duckworth, who warns the emotions Americans are experiencing may linger.

"When Kennedy was assassinated, that was a loss and a tragedy, but everybody knew it was over," he says. "This has an unsettling quality of not necessarily being done. It's more than you can bear."

Copyright 2001 The Associated Press. All rights reserved.