Sarah Gooch was at home, tending to day care children. Jessie Mommens was a student in high school, sitting in a Des Moines classroom. Eric Mattson happened to be in church -- he served as associate pastor for a congregation in Joplin.

"I just remember it being really scary," Mommens said. "The world stopped."

Twenty years after the Tuesday morning in 2001 now etched in history as 9/11, the terrorist attack that killed 2,977 people and brought down the World Trade Center towers continues to resonate.

Mexico resident Ed Williams was there, heading to work in New Jersey. When the first plane struck, he was seven stories below the towers, stepping onto a train. When he arrived a his office, a co-worker broke the news.

Williams couldn't believe it. He was just there and witnessed no commotion, nothing but an ordinary commute. But he went to a window overlooking the Manhattan skyline.

"I saw the second plane hit," he recalled. "It was surreal. It was intense."

Later in the day, with trains shut down, he returned to his workplace only to find a woman in tears repeating "they're gone, they're gone."

Barb Swaim was preparing for lunch in the Community R-6 kitchen when someone burst in with the news.

"We were all shocked," she said.

Jessie Mommens, now Community's elementary school principal, was a high school sophomore. The teacher heard from someone and switched on the classroom television. Gooch didn't have the television on at her home daycare. Her husband called from work.

"My brother lived in that area, so I immediately called him and he answered," she said. "He was talking about the smoke, the smells."

Williams ventured to Manhattan the next day. He remembers the fumes vividly. But he struggles to conjure up words to describe them properly.

When he sees the images from that morning, however, it all comes flooding back.

"I feel it all over again," he explained. "The anger, the fear -- it hurts all over again."

Mattson turned to prayer, for the victims, the families, the first responders.

"The images that haunted me the most were of people falling from the buildings," he pointed out. As a pastor he studied other religions and knew many Muslims. One called to ask "are we still friends."

"I didn't think of it as one religion attacking another," said Mattson, who now serves as pastor of Mexico’s United Methodist Church. "I saw it as an act of evil, men using religion to their own ends."

Randy Hernandez recently graduated from Mexico High School. He grew up in the aftermath of 9/11, hearing stories from his parents.

"We can't really understand, since we didn't live through it," Hernandez said of his generation. "We can only learn from it."

People continue to learn. Gooch, a teacher at Mexico High School, visited the location recently.

"To go there was an extremely solemn experience," she observed, pondering if "solemn" could truly define the emotions. "It seems like it was a lifetime ago."

And yet, as everyone who witnessed the events of that day in person or on television points out, 9/11 will always be a day to remember.