BRAINTREE -- Colleen Donohoe will never forget the smell.

"I can't explain it," she said. "Still chokes me up. It was the smell of death, the smell of evil."

Almost 25 years ago, Donohoe and two other youth ministers from the Archdiocese of Boston were standing on what she called the "edge of despair," overlooking the spot where, weeks earlier, the World Trade Center stood. The stench was horrid. Hundreds of rescue workers were combing through the mountain of wreckage known as "Ground Zero," or simply "the pit." A police officer had taken Donohoe and the others to see the site, past an endless series of checkpoints. The officer shouted. The wind had changed direction, and soon the four of them were covered in ash. They were silent. There were no words to describe what was around them, what was seeping into their skin and clothing.

"You immediately knew that it wasn't just ash from buildings," Donohoe recalled.

At age 29, she was one of 21 Boston youth ministers who volunteered at Ground Zero after the 9/11 attacks. What she witnessed at Ground Zero a quarter of a century ago formed her.

"It's made me more awake; it's made me more alive," she said, "understanding the urgency to be Christ for others, to be hope and light in the darkness."

Boston's clergy, religious, and laypeople answered the call to serve in the aftermath of the attacks. Parishioners raised over $1 million in a special collection for relief efforts, the biggest in archdiocesan history at the time. People rushed to give blood, donate money, and offer prayers. Priests presided over memorial services and comforted victims' families.

"You do what you have to do," said Father Richard Uftring, who served as chaplain of Our Lady of the Airways Chapel in Logan Airport during and after the attacks.

American Airlines Flight 11 and United Airlines Flight 175, the two planes terrorists flew into the twin towers of the World Trade Center, took off from Logan. On the morning of Sept. 11, Father Uftring received a call from American Airlines saying that one of their planes "had been taken over." He arrived at the airport and found "chaos."

"It was just surreal," he recalled. "Nobody could grasp what was going to happen in the next few hours."

Airline staff were stuck on the ground, waiting for any scrap of information. People screamed and demanded to know if there were any survivors. Their hopes were quickly dashed when the scale of the attacks became known. It was impossible to grieve or talk about what had happened, because no one knew the details. The Logan Airport Hilton became a meeting place for victims' loved ones. Father Uftring knew several flight attendants who were killed.

"Those weren't just planes," he said. "Those were family members."

He had no idea what to do. He walked around and prayed the same words over and over: "God, you put me here. Get me through here."

"It was pandemonium," he said. "You couldn't even stop to pray. All you did was hold people. People were absolutely falling apart with emotions."

Attending countless memorials, he has met many more victims' families. Three days after 9/11, a candlelight prayer service was held at the Hilton. Father Uftring recalled all of the candles lighting up, their reflections flickering on the roof above. They looked like stars. The hotel is now "a spiritual place" for him.

"We felt each other's pain, brokenness," he said.

At the time of the attacks, Donohoe was a campus minister and theology teacher at St. Margaret Elementary School and Msgr. Ryan Memorial High School in Dorchester. It was one of the toughest days of her ministry. She and the rest of the faculty had to come up with age-appropriate explanations for what had happened, why students' parents had come to pick them up early, and why their classmates weren't in school the next few days. A friend of hers in New York was killed. The world had changed for her and her students. Her job, however, remained the same: "To lead them to the Lord."

"My faith was never shaken by it," she said. "My faith in humanity, for sure, but my faith in the Lord never wavered."

She needed to feel God's presence and bring that presence to others. That, she said, was what brought her to Lower Manhattan. Young people in her ministry "begged" to go to Ground Zero, but she was initially reluctant. She ended up making four trips to the site in the year following the attacks.

"It was important for them to see, not the horror, but the beauty that can rise from the ashes," she said.

Her first assignment was an overnight shift outside the morgue, bringing coffee, hot cocoa, and a smile to rescue workers transporting human remains. Don't talk to them, she was warned. If they did want to talk, her job was to listen. She listened to workers at the morgue and in Staten Island, where volunteers sifted through recovered personal items -- clothes, wedding rings, scraps of paper -- in hopes of identifying victims. St. Peter Church, so close to the towers that a piece of one of the planes hit its roof, was a headquarters for rescue workers and volunteers. Youth ministers helped first responders, some working 24/7, set up email accounts so they could message their families. Donohoe offered coffee and prayers, praying the rosary while walking around the church. She gets choked up when she remembers the firefighters.

"It was a brotherhood, that they were united in arms and that they were going to do whatever it took to make this right, to somehow find beauty, truth, and goodness," she said.

Everyone in St. Peter's was united. They relied on one another. The whole country was like that after 9/11, she recalled, "but we have forgotten."

"This was not a time to turn inward," said Father David Michael. "It was a time to reach out."

In 2001, Father Michael was the Archdiocese of Boston's liaison to the Jewish community and a chaplain at Brandeis University. He helped organize an interfaith prayer service that took place at Boston City Hall on Sept. 13. An estimated crowd of 10,000 to 15,000 people attended.

"We were really stunned," he said.

Christians, Jews, and Muslims participated in the prayer service, joined by a message of religious tolerance.

"Boston rose to the occasion," he said, adding that he could not recall any local hate crimes following the attacks.

The Archdiocese of Boston had initiated dialogues with the city's Muslim community in the late 1990s. Father Michael said they were "eager" to participate in the prayer service with the archdiocese.

"We did not want the event of the loss of so much life to divide us as a community," he said.

The archdiocese invited ecumenical and interfaith leaders to a meeting at the archbishop's residence, then located in Brighton, for a follow-up meeting. Father Michael could not recall any such meeting happening before in the archdiocese's history.

The meeting's purpose, he said, was "to see how we could serve the people of America."

"How could we serve our own people?" he added. "How could we serve the wider community in this time of horror and fear and sorrow?"

Father Uftring is still processing his emotions from that day. He has not been to the Sept. 11 Memorial in New York City because it would be too difficult, but he did visit Ground Zero with airline crew members. They left roses at the site.

"To see the magnitude of the devastation, the total chaos that was caused, it was overwhelming," he said.

Recently, he met a 94-year-old man whose son was killed in the World Trade Center at Incarnation Parish in Melrose, where Father Uftring is a priest in residence. The two men spoke about how the attacks had changed their lives.

"You're feeling it, and they're feeling it, and you have something in common," he said.

He plans to call the man and tell him he's thinking about him and his son. If possible, he wants to attend the memorial ceremony at Logan Airport. As he stands on the tarmac, the memories will come back.

"I did what I was called to do, and I pray to God I did the right thing," he said.

Donohoe can recall many images from Ground Zero. The ubiquitous posters of missing loved ones. People walking around in silence, holding photos of those they were searching for. One memory gives her hope: the cross-shaped beam salvaged from the wreckage, which became an icon of the city and country's recovery.

"People say, 'Where was God?'" she said. "'Where was God on that day?' Well, he was there. He was in that pit with them, and he's in the pit of the mess and the sin of us, and he's the hope that rises from the ashes."