Word of the killing stunned the middle-class Tacony neighborhood where the victim and killer lived.
``We are all in total shock,'' Lewis' aunt, Karen Schiavo, 35, said last night. ``How can someone, another girl, be so violent as to stab another person like that? What is this society coming to? My sister is still shaking and my brother-in-law is telling himself, `I've lost my daughter. Now what do I do?' ''
The slaying took place at a neighborhood carnival in Russo Park sponsored by the Mayfair Athletic Club; Lewis' 8-year-old brother plays basketball for the club.
Police declined to release many details of the slaying, but a friend of the victim, Michelle Luciano, 16, said in an interview last night that she, Lewis and a third girl were walking past a merry-go-round ride at roughly 10 p.m. Friday when the fatal confrontation began to unfold.
According to Luciano, another group of three girls was on the ride, spotted Lewis walking by, and pointed at her and yelled something at her. Lewis shot a look back at the girl who had gestured, Luciano said.
Lewis hadn't been able to make out what was said about her because the words were drowned out by the carnival music. ``What did she say?'' Lewis asked Luciano.
Then the ride came to an end and the trio got off. They walked by Luciano, Lewis and the other friend. Lewis then looked at the girl who had gestured at her and asked, ``What's the problem?''
The girl denied there was any problem and walked off.
Luciano said she and Lewis and their friend had never seen the other girls before.
About 10 minutes later, Luciano said, two of the girls who had been on the ride returned with a third girl. Missing from the group, however, was the girl who had first gestured at Lewis, Luciano said.
There was a new exchange of words. Suddenly, one of the girls began shoving Lewis, who shoved back, Luciano said. At that point, this girl pulled a knife - a pocket knife with a three-inch blade, police said - from a backpack and stabbed Lewis in the chest.
``The next thing I know Christa flew backwards and fell onto me,'' Luciano said. ``She was holding her chest. She could barely talk. I heard her say in a whisper, `Guys, I can't breathe.' ''
The girl who did the stabbing ran north on Cottman Avenue, accompanied by her friends, Luciano said.
Police said the suspect was arrested at her home on Cottman Avenue a short time after the slaying.
Lewis' fatal knifing was highly unusual for the middle-class neighborhood. Philadelphia police homicide statistics for the 7,500-resident census tract that includes Russo Park, where the killing took place, and its nearby homes show that her killing was the first there since at least 1990.
That entire section of Northeast Philadelphia, which has a poverty rate half the city average, has had a murder rate well under the city's. The area's rate is only about three deaths per 100,000 residents - versus a citywide annual rate of about 28 slayings per 100,000 people.
The carnival continued last night and many friends and sports teammates of Lewis from St. Hubert's High School gathered there. They built a memorial of flowers, pictures of Lewis and her friends, and teddy bears.
Relatives and friends described the blond-haired, blue-eyed Lewis as a ``golden girl.''
They said that she was a top student, a member of the school soccer team and a lacrosse player. She worked weekends at the nearby Dunkin' Donuts and often babysat her younger siblings, ages 13, 8, and 4, according to Schiavo, sister of Joann Lewis, the victim's 36-year-old mother.
Last night, Schiavo, who was still at the Lewis home - a few blocks from the carnival - trying to comfort the stricken parents, said that Lewis' parents told their daughter to have a good time as she and two girlfriends left for the carnival about 9 p.m. Friday.
While carnival music played in the background and children screamed with delight, teenagers sobbed as Christa's classmates and friends paid homage to their slain friend during a candlelight vigil on the carnival grounds.
``She was nice to everybody; she would make everyone in her classes laugh,'' said Jill Chaudrue, a 15-year-old sophomore at St. Hubert's. ``It is so weird to say goodbye to someone on Friday after school and all of a sudden you will never see them again. I can't imagine not seeing Christa Monday morning.''
Lewis was not only academically talented and athletic, but she also was popular. She had just been asked to the prom the night before her death, according to her aunt.
``She was so cute,'' said neighborhood friend, Mike Dieterle, 20. ``She was great to hang out with.''
Among those at the carnival vigil last night were John and Kathy Polec, the parents of Eddie Polec - the 16-year-old Fox Chase youth who was beaten to death by a group of suburban youths on the steps of a church over an imagined insult. The Polecs declined comment.
Donna Petersen, president of the Mayfair Athletic Club, which sponsored the carnival Friday night, issued a statement yesterday expressing sympathy for Lewis' family. She said the carnival could not be canceled for contractual reasons.
``The family carnival held at Russo Park is intended to provide fun and recreation to our neighborhood families as well as act as a fund-raiser for our extensive youth programs,'' Petersen said. At the Lewis home, several friends and neighbors continued to stop by late last night. Schiavo sat on the porch, her head buried in her hands. She said she hadn't slept for 38 hours.
Schiavo said the family is making funeral arrangements for early this week.
``It will take a long, long time to heal from this,'' she said, fighting back tears.
``Christa was going to be my bridesmaid for my wedding in October. She picked out the gown and everything. She loved that dress so much that we've decided to bury her in it.''