He was known as a quiet and polite boy who often helped a neighbor with chores without being asked. He was so honest that when he and his best pal were treasure hunting in the woods behind their townhouse development and found a bag of jewelry, he insisted that they turn their discovery over to police.

Yesterday, the day after a Prince William County community dodged a potentially violent tragedy, students, teachers and parents gathered at Bull Run Middle School to pick up backpacks and report cards and talk to counselors. The atmosphere was in sharp contrast to Friday, when the school was locked down and students evacuated after a vice principal found the 12-year-old boy in a restroom with a loaded rifle and two other guns.

In the boy's subdivision, there was surprise that the seventh-grade student, a Boy Scout and one of two sons of what one neighbor called a "good Christian family," had been arrested and relief that no one had been injured or killed.

Friends and neighbors did not see the boy's actions coming. His friends said that the boy was constantly teased and bullied on the bus and in the schoolyard, corridors and cafeteria about his weight, his big glasses and his style of dress but that he never reacted to it.

The only hint of what happened Friday was in September, at the start of the school year. The boy told his best friend in the townhouse development and other school friends that he wanted to take over the school, hold hostages and extort money and a helicopter to fly him out of the country. When his schoolmates did not take him seriously, he stopped talking about the plan until a couple of weeks ago.

"Everybody thought he was joking," said his best friend, who was standing on a scooter yesterday morning next to his mother outside their home. The mother asked that neither she nor her son be identified.

The 12-year-old boy arrested at the school and his mother, Naomi Lewis, 38, of Haymarket, are expected to be arraigned tomorrow on charges of possession of a weapon on school property. Lewis, a cafeteria worker at the school, was released on $5,000 bond. The boy, who also faces charges including conspiracy to commit murder, was being held without bond at the Prince William Juvenile Detention Home. The Washington Post does not identify by name juveniles who are arrested or accused by police of crimes unless a judge or magistrate has ordered that they be tried as adults.

The parking lot of Bull Run Middle School was full of minivans, sedans and SUVs yesterday, many of them proudly pasted with school bumper stickers. A police cruiser was parked at the lot's entrance, and several officers stood at the entrance of the school. There was a steady stream of students and parents in and out.

School officials opened the doors yesterday so that students could retrieve belongings that were left behind Friday when they were evacuated. Counselors were also at the school to talk to students. A county schools spokeswoman said that 19 students signed up for formal counseling and that others spoke to counselors informally.

Some parents talked about how fortunate they were that the boy was discovered before he could initiate his plan. The boy had sneaked three guns into his mother's car before they left for school. About 8:30 a.m., he retrieved the guns from the car and took them to a school restroom.

He was popping a cartridge into a .30-06 rifle when Assistant Principal Jamie Addington happened to walk by. Addington, who hunts deer, geese and ducks, "knew instinctively" that he had heard the sound of a gun being loaded, said his wife, Sherry.

Sherry Addington said her husband looked under the door of a stall and saw a boy, who had helped him set up tables in the school cafeteria, with a loaded .30-06 rifle. He was shocked, Sherry Addington said, to see that the boy had two other weapons -- a rifle and a shotgun -- but remained calm. He called police, and the school quickly implemented an emergency plan that had been practiced a few times before.

Jamie Addington could not be reached to comment yesterday, but his wife called him a "real hero."

"That's very much in his nature, looking out for children and the school," she said. "I think if he hadn't been there exactly when he was, the situation would have been a lot worse."

Sherry Addington, a choral teacher at Lake Ridge Middle School in Woodbridge, said her school, like Bull Run, has a school violence response plan. But she has never imagined that a student might bring weapons to her school or her husband's, she said.

"I can't, and I don't want to" imagine such a scenario, she said. "But it could happen anywhere."

When Principal William Bixby announced on the school loudspeaker during first period that there was a student with a gun in the school, that administrators were initiating a lockdown and that students should get under their desks, some thought it was a joke.

"Once the teacher shut off the lights and locked the door, we knew it was real," said Brian Wanzer, 13, a neighbor and classmate of the boy charged.

Brian's mother, Vanice Wanzer, was friends with Naomi Lewis in high school, and they renewed their friendship several months ago when the Wanzers moved into a townhouse two doors down from the Lewises. Neighbors said the Lewises have lived there since the early 1990s.

"I just want everyone to know that this is a good family, a good Christian family," she said.

Brian Wanzer said that when the 12-year-old got on the bus, other children would tease him, saying, "Where do you get your clothes, Wal-Mart? Don't you ever brush your teeth or wash your face?"

Vanice Wanzer said other parents were unaware of the bullying and teasing the boy had endured for years. "He never answered back, never cussed anyone out. He just kept quiet when they did it," her son said.

She said she is convinced that the boy would not have fired the guns, that what he did was a cry for help. She pointed to a bracelet on her wrist that she had bought from the boy at a yard sale. It was one of several pieces of jewelry he had found on his treasure-hunting trip.

The mother of the boy's best friend said he turned the jewelry over to police after he found it. When no one claimed it in 30 days, police returned it to the boy.

Wanzer was quiet for a minute and then said, "I'm still trying to figure out if that really happened yesterday or not."