Anthony Yacapino was sitting at home, watching a Bugs Bunny cartoon in 2004 when he felt the first signs of post-traumatic stress disorder. "My heart felt like it was leaping out of my chest. I thought I was dying. It was seriously scary," he recalls.

The retired New York City police detective, like thousands of colleagues, worked for months after the Sept. 11, 2001, terrorist attacks dealing with the aftermath. He interviewed relatives of the dead at a bereavement center and later searched for human remains and victims' belongings at a Staten Island landfill.

After that first scare, Yacapino remained silent for months, trying to avoid letting on to his superiors that he was ailing years after working near ground zero. Then he had to go to court one day in lower Manhattan, not far from the World Trade Center site, and he went into a panic attack.

That's when he finally decided to seek medical help, enlisting in a program run by Stony Brook University on New York's Long Island. "The best move I ever made," he admits.

The WTC Medical Monitoring and Treatment Program at Stony Brook has cared for 6,000 first responders. Police officers, firefighters, construction workers and others receiving treatment at the program are videotaped recounting their experiences. A documentary featuring their recollections, with a companion book titled "We're Not Leaving," are being released to mark the 10th anniversary.

Dr. Benjamin Luft, the program's director, said 150 recordings have been compiled, and his goal is to collect 911 remembrances by Sept. 11, 2012. Eventually, they will be sent to the American Folklife Center at the Library of Congress.

"A major part of our documentary deals with memory and remembrance and not forgetting," Luft said in a recent interview. "In many ways, many of the things that have been reported on the responders have been reported by others. We just basically wanted to hear what those responders had to say."

The title of the book comes from a police officer's account of the moments after a jetliner hit the north tower of the World Trade Center. She tells of encountering an FBI agent at the chaotic scene, where people were desperately jumping to their deaths from high above before the tower ultimately collapsed. "We're under attack. You're going to die if you stay here," the agent warned her. The officer, who survived, responded like many others who shared her sentiment, if not her luck: "We're not leaving."

Luft said that 10 years on, new patients are still walking into his center seeking treatment, many of them police officers and firefighters who realize they need help only after they retire.

"All of a sudden they're out of that situation and those feelings and those conditions come to the forefront," Luft said. "For them, the real disaster to their lives that would occur is really when they're not able to do their job, when they're not able to function fully, when they're not able to be part of that community, to be able to be a responder."

Eddie Burns, 44, was a patrolman living in Brooklyn on the morning of Sept. 11, 2001. He was off duty, walking to a coffee shop with his young daughter when he saw a second jetliner fly low overhead, heading for the Trade Center's south tower. After seeing the huge fireball, and hearing a call for all emergency personnel to report for duty, he arranged for his daughter's care and raced to the scene.

"We did everything," he recalls. "Search and recovery, evacuation, we searched cars; there were a lot of abandoned vehicles. There were no survivors.

"The only people we were able to help were the other responders."

He later spent time at the landfill where debris from ground zero was taken and searched for remains. He spent five more years as a police officer, before deciding to retire in 2006 with only 10 years on the job.

"Those last five years were the longest years of my life. I was so depressed and unhappy," he said.

He and his family now live on eastern Long Island. He said he went to Stony Brook because "I was basically afraid for my life. I didn't know what I was exposed to with the toxins (at ground zero)." He said he was diagnosed with an inflammation of the sinus cavity and also felt some effects of post-traumatic stress disorder.

"I feel a lot better now," he said. "There was an office for us to go to and kind of vent, share our lives with them."

Luft said as the 10th anniversary approaches, there is some expected anxiety, but he noted first responders come at the date from a different perspective.

"If we use 9/11 with authenticity, with frankness, with respect, with no aversion to the truth, I don't think that will distress them."