Fairfax County's acting police chief said last night that arrests are imminent in Monday's machete attack on a 16-year-old boy and that to discourage further gang violence, she has stepped up police presence in malls and other places where teenagers gather.

"We know who we are looking for," acting Police Chief Suzanne G. Devlin said during a community meeting on gang violence at Lake Braddock Elementary School scheduled before the teenager was assaulted. "I hope it offers some comfort that these kids are going to be located. Obviously, there are some larger community issues."

Police said the attack, in which the 16-year-old's hands were mutilated by a machete, was the latest act of revenge in a running feud between the two largest gangs in Northern Virginia.

The 16-year-old victim, who remains at Inova Fairfax Hospital, is a member of the South Side Locos, a relatively new but growing gang, police said. They said the suspects are believed to belong to Mara Salvatrucha, or MS-13, one of the most violent gangs in Northern Virginia.

The 16-year-old was walking along Edsall Road about 1 a.m. Monday when he was attacked by several people, one wielding a machete, police said. The youth lost four fingers on his left hand, and his right hand was nearly severed, his doctor said. Devlin said the slashes to the victim's hands were defensive wounds that occurred as he tried to fend off machete blows. She said she expects the suspects to be arrested within 48 hours.

Although Fairfax police said the victim was a member of the South Side Locos, his parents said yesterday that they saw no signs that their son was in a gang and don't understand why anyone would hurt him.

"I don't know why they would do this," said his father, who came with his wife to the United States from El Salvador 30 years ago. The parents agreed to be interviewed on the condition that, to protect their son, they not be identified. "He was not a saint, but he was not bad," his mother said. "He had small fights with people, but it was the normal things of teenagers."

His parents said they had not spoken to their son because he remains sedated at the hospital, where he is recovering from seven hours of surgery.

"The doctors said he will have a long, long rehabilitation," his mother said in Spanish, holding a photograph of her son and his girlfriend taken three weeks ago at the girlfriend's quinceanera -- a coming-of-age party for a 15-year-old girl. "I don't know if he will ever be able to use his hands again."

The mother said that after an official at her son's alternative high school, Richard Milburn High School, had a discussion with her about gang involvement, she searched for any signs of gang activity. Other than a penchant for wearing baggy clothes, which she noted many teenagers wear today, she saw no such signs: no drawings, no bandannas, no tattoos.

When told that classmates said he had the initials of SSL on his knuckles, his mother angrily denied it.

"That is not true at all," she said. "He did not have that on his hands or anywhere. I work very hard . . . for the life I have here. I would not have a gang member in my home. If that were true, I would turn him over myself."

She described her son as a shy, reserved person who liked to draw and play Nintendo. He was on his way to the 7-Eleven with his girlfriend when the attack occurred early Monday, his mother said.

But at his 55-student school, teachers and classmates said the quiet and unassuming student sported gang tattoos and colors. Some students were curious about the attack, while others seemed indifferent. One class began the day by reading a newspaper story on the attack and held a discussion about gangs.

"I used the incident to emphasize that it was not a good idea to be associated with a gang," said Deborah C. Brown, the school's director. "They pretty much agreed with that. They were saying, 'You can't mess with the gangs, because they don't play.' "

Irene Prescott, the school's psychology teacher, said the 16-year-old approached her once when a student tried to pick a fight with him.

"Some bigger kid at the school wanted to start trouble, and he didn't want trouble. He just wanted to go to school," said Prescott, whose classroom has a poster the youth drew of a human head and brain, with labels pointing to parts of the brain such as the hypothalamus and cerebral cortex.

The school's security chief, Leroy Washington, said the attack caused intense curiosity among students. "They were saying: 'Why didn't he run? Why was he out there at night like this by himself?' " He added: "Some people thought he really wasn't in the gang and that he was just trying to be cool. They were saying, 'Where was his posse?' Most of the time, gangs have a posse."

Christian Rodriguez, 18, said the teenager often talked about his membership in the SSL and about the rivalry with MS-13. The youth told "war stories" about his gang life, he said.

"He would talk about how 'last week, I saw some MS dudes, and we fought, then, we would have bats and we'd just fight somewhere off Route 1,' " said Rodriguez, who sat next to the teenager in science class.

"He didn't have an attitude, but he carried himself like if someone steps up to him, he would be like, 'I'm going to crush him,' " Rodriguez said. "My guess is that he fought back. He doesn't back down and run."

Devlin said even though many resources are available for at-risk youth in Fairfax, more has to be done to reach out to teenagers who are vulnerable to gang life.

"The larger community question is what do we do with these kids who feel like they don't have a home in Fairfax County?" she said.

Staff writer Ian Shapira contributed to this report.