POMONA, Calif. (AP) _ A teen-age gang member was arrested Friday in the shooting attack that wounded four people, including an 11-year-old boy, in a crowd of 100 people at a park meeting on alternatives to gang violence.

The youth, whose identity was not released, was booked for investigation of attempted murder and alleged parole violations. He gave police information that may lead to other arrests, police Detective Gary Elofson said.

The victims, all of whom were shot in the back, were watching a movie put on by Pomona Victory Outreach in Harrison Park when the assailant approached Thursday night and began firing without warning, police said.

The apparent gang-related shooting occured Thursday night during a showing of the movie ''The Duke of Earl'' by Victory Outreach, an organization working to end gang violence and drug abuse.

The gunman was alone and said nothing before he began shooting into the crowd, witnesses told police.

The most severely injured was Charles Wagner, 37, who underwent surgery and was in serious condition at Queen of the Valley Hospital Friday, said hospital spokeswoman Sophia Lima. A 24-year-old man and an 11-year-old boy were hospitalized; a 35-year-old man was treated and released, she said. All four were from Pomona.

''We just didn't expect that at all. We have shown the movie many times before (in gang areas) ... and nothing like this ever happened,'' said Nora Uribe, wife of the church pastor, former gang member Mark Uribe.

The Pomona church, organized seven years ago to provide alternatives for drug addicts and gang members, operates a drug rehabilitation program and seeks to dissuade gang members from violent activity. The church conducts street rallies, concerts and other activities, Mrs. Uribe said.

Pomona, a city of more than 100,000 in eastern Los Angeles County about 30 miles from downtown Los Angeles, has several Hispanic and black gangs. In April, gunmen opened fire on a crowd of mourners at the funeral of a slain gang member, wounding four people, police said.