From Newsstand Correspondent Art Harris

LITTLETON, Colorado (CNN) -- When she heard police sirens on the morning of April 20, Sherry Higgins raced to Columbine High School, where her children attend classes.

Arriving even before paramedics as police officers carried out the first wounded students, Higgins stripped off her blouse to use as a tourniquet, working in her halter top, trying to help as police brought carload after carload of wounded students.

"I was one of those people up there saying, 'Blow those shooters away, please. Why haven't you cops got in there and blown those guys away?'" she says. "I don't care who they are. Blow them away. They're killing our children."

But then, from the wounded students, Higgins learned the identities of the killers -- Dylan Klebold and Eric Harris. They were friends of her daughter, fringe members of an outcast group nicknamed the Trenchcoat Mafia who often met at her house.

"They hung out here quite a bit. They're all good kids," Higgins says. "Eric had been over here. He seemed very sweet. Played Nintendo, laughed, had a good time. Joked, drank soda pop, had hot dogs. All-around good kid."

Higgins' daughter, one of the Trenchcoat Mafia, was in the cafeteria line at Columbine when the attack began. Her son, Chris Markham, was also in the line of fire.

"My friend Sean, I saw him get shot. He went down to the ground," Markham says. "I saw my friend Lance get shot. He went down to the ground. I saw my friend Dan get shot."

Only after Higgins found her children safe at home did she tell them who the gunmen were.

"They didn't seem like the killer type," Markham says. "When I heard it was them, I was kind of shocked because they had been in my house."

RELATED VIDEO
Watch the Video Report "They Hid it Well"
Windows Media	28K	80K

"These kids hid it from everybody," Higgins says. "They hid it well."

Eric Harris, the son of an Air Force pilot, grew up in a military family that moved around. When he was eight, his father, Wayne, was stationed at Wurtsmith Air Force Base in Michigan.

Eric competed in community fishing contests. One former classmate remembers him as a normal, fun-loving, but shy, kid.

Bill Stone, who lived across the street, recalls how Eric and his older brother, Kevin, played basketball with their father, who was a youth sports coach.

"It just seem a very close-knit family," Stone says. "I watched Wayne put in a basketball backboard, and he would get out and play with his boys. They just had a good time playing together."

Next, the Harris family was transferred to Plattsburgh, New York, where Eric entered fifth grade. Little League coach Bryan LaPier says Eric's father wanted his son to play baseball so he could make friends and remembers that Eric liked the sport.

Then in 1993, Wayne Harris retired from the Air Force, took a job at a flight training school and moved his family to Littleton, Colorado. A former Little League teammate says Eric didn't want to leave his friends in New York.

Once again, Eric was the new kid in school. In an algebra class, he became acquainted with Dylan Klebold, the son of a geophysicist and a special education counselor.

The two boys had a lot in common. They were quiet, had older brothers and loved computers. Like Eric, Dylan had played in Little League, though he would reportedly refuse to play if he didn't get to pitch.

"(Dylan) was in my Cub Scout troop, and then I picked up with him again in the seventh and eighth grade," says Nick Baumgart, who grew up with Klebold. "He was a good kid back then, you know, (a) quiet kid, intelligent, always respectful to teachers."

Baumgart met Harris in the seventh grade. "He was smart, he was a little different than Dylan and I. He was, maybe, a little bit more kind of easily agitated," Baumgart says. "He harbored grudges, I guess, in the worst I could say about him."

"Dylan was more of a follower. And so wherever Eric was, Dylan was real sure not to be too far behind."

In the seventh and eighth grade, Dylan and Eric began to get heavily involved in playing violent computer games. "It was kind of where they would come home after school and start playing and then wouldn't stop until they went to sleep," Baumgart says.

By the time Eric and Dylan entered high school, both seemed to have become loners. As the distance grew, Eric began to call himself "Reb."

"There definitely were groups, cliques, you know, and Eric and Dylan kid of didn't fit into any of them," Baumgart says. "They kind of tried to latch onto the Trenchcoat Mafia."

During his freshman year, Eric met Tiffany Typher in German class and took her to Homecoming. She says it was their only date, and when he refused to go out with him again, she says Eric staged a suicide prank, sprawling on the ground with fake blood splashed all over him.

In Tiffany's yearbook, Eric later wrote, in German, "Ich bin Gott." Translated, it means "I am God."

By their junior year, Eric and Dylan seemed to be changing for the worse. They broke into a car and were sentenced to a year of community service.

The parents of a classmate also filed a police complaint against Eric for threatening their son and breaking the windshield of his car.

Toward the end of the 1998 school year at Columbine High, one of the boys filled a diary with thoughts of hate and violence. Soon both boys changed their appearance. Dylan Klebold no longer looked like his junior yearbook picture.

"This year, he had long blond hair and he had a big goatee and he looked a lot, a lot different than he did in (that) picture," says classmate Jason Rauzi.

By their senior year, Dylan and Eric were wearing the unofficial uniform of the Trenchcoat Mafia -- all black or military fatigues and at times long coats reminiscent of gunslingers or the Gestapo.

In fact, friends say both boys were enthralled with Hitler and the Third Reich.

Some players on Columbine's winning football team saw the Trenchcoat Mafia as losers.

"The jocks, the football players, they would push them up against the lockers, call them fags, (make) rude comments, basically," says classmate Nicole Schlieve.

Other athletes say they only ridiculed the Mafia about the way they dressed.

"I think that they kept their distance away from others and felt that they were almost different than all the rest of the kids in school," says classmate Jason Jones.

This past fall, for a class project, Eric and Dylan made a video. They cast students as gunmen in long coats shooting athletes in the school hallways.

Sherry Higgins says she was told it was a spoof, a "bang-bang, Dick Tracy-type thing that they were trying to put together." In hindsight, she admits it should have been a clue.

On a computer Web site thought to belong to Eric, there were a collection of lyrics from a German industrial rock band: "Apocalypse now. Walls of flame. Billowing smoke. Who's to blame?"

On Friday night, four days before the Columbine shootings, both boys worked their jobs at Black Jack Pizza. Saturday night was prom night, and, to the surprise of some, Dylan brought a date.

Then on Sunday, Dylan's used BMW was parked outside the Harris home for hours. Neighbors began to hear loud noises coming from behind the closed door of the family garage -- power saws and glass breaking.

Neighbor Matthew Good remembers Eric's parents being there for part of the weekend and gone during another part.

On Tuesday, April 20 -- Hitler's birthday -- Eric and Dylan skipped school. As lunch hour began, Brooks Brown saw Eric in the school parking lot.

"I asked him, like, why he was acting strange. He said, 'Um, Brooks, I like you, I like you. Now go home, get out of here.' So I took off, because he's not one to be toyed with," Brown says.

Moments later, Brown heard the gunfire that left a dozen schoolmates and a teacher dead. Nick Baumgart escaped, only to learn that his prom date, Rachel Scott, was among the victims.

In the midst of the chaos, he had a chilling thought.

"Just hearing the booms in the background as you're running, and you know, loud booms, not like gunshots ... I just kind of knew it was Eric," Baumgart says.

He later found that his childhood friend, Dylan Klebold, had followed Eric Harris to the end.

"There's no way to explain it," he says. "The whole thing is so illogical. There's nothing you can do to explain something like this. You know, you just kinda got to move on."