Richmond, California (CNN) -- Police investigating the gang rape of a 15-year-old girl have arrested five people, a police spokesman said Wednesday.

Three juveniles and two adults are in custody in the rape on Saturday, said the Richmond police spokesman, Lt. Mark Gagan. The three juveniles will be charged as adults, he said.

Gagan said the suspects will face several felony charges in the incident, including "rape in concert," and that the suspects would all face the possibility of life in prison if convicted.

Gagan also said the victim was released from a hospital Wednesday, four days after the attack.

Authorities have described the incident as a two-and-a-half-hour assault that occurred on the Richmond High School campus, in the Richmond community north of Oakland on San Francisco Bay.

Gagan said police arrested three of the suspects Tuesday night. They included Salvador Rodriguez, 21, as well as a 16-year-old and a 17-year-old whose identities were not released because they are juveniles, he said.

A 19-year-old, Manuel Ortega, and an unidentified 15-year-old were arrested earlier, he said.

On Wednesday, students, teachers and area residents gathered to defend their city's image.

Those gathered at Richmond High School witnessed "a response that is really from the heart, and also from the gut, given the mourning, the sadness, the anger that has arisen since Saturday," Prishni Murillo, executive director of Youth Together, an area youth leadership organization, said at a news conference.

"We do not want this incident to be an excuse to further criminalize the young people of this city," Murillo said.

Senior Norma Bautista echoed that sentiment.

"We are not criminals," she said. "We come here to this school because we want [there] to be a change."

Lorna McClellan, a Richmond High teacher, said it was wrong that the community was being portrayed as a place that does not stand up for victims.

"Yes, something horrible and atrocious happened on our campus, and yes, blame lies with the school officials, with the teachers, with the district, with the police, with the students were afraid to speak up. But it's important to realize that our community realizes this is a problem, and we are taking active steps to fix it," McClellan said.

Gagan said Wednesday that police expect to make further arrests.

Watch a discussion with Gagan

As many as 10 people were involved in the assault in a dimly lighted back alley at the school, police have said, while another 10 people watched without calling 911 to report it.

A 1999 California law makes it illegal not to report a witnessed crime against a child, but the law applies only to cases in which the child is 14 or younger.

Police have posted a $20,000 reward for anyone who comes to them with information that helps arrest and convict those involved in the attack.

The victim was found unconscious and "brutally assaulted" under a bench shortly before midnight Saturday, after police received a call from someone in the area who had overheard people at the assault scene talking about the incident, police said.

The girl was flown by helicopter to a hospital, where she was admitted in critical condition.

