San Jose police announced Monday morning that they had made an arrest Sunday in Friday's shooting at the Westfield Valley Fair Mall, which left three people injured, and which authorities say was gang-related.

One 17-year-old male suspect was in custody as of Monday in the Black Friday shooting that caused panic and sent crowds scattering at the Valley Fair Mall, on the San Jose-Santa Clara border. San Jose police posted the photo below, showing the suspect turned away from the camera, handcuffed, with his head obscured by a black box, with the phrase, "We got him."

A subsequent news conference Monday evening with San Jose Police Chief Paul Joseph, San Jose Mayor Matt Mahan, and Santa Clara County District Attorney Jeff Rosen revealed that the suspect is a juvenile who previously was arrested in February for carrying a concealed weapon — though he avoided criminal conviction through a deferred judgment, as Bay Area News Group reports.

The suspect reportedly came to the mall with a girlfriend — and possibly the couple's child — with a handgun tucked into his waistband. And Joseph stressed that the suspect and the adult male victim who was shot in the altercation did not know each other, but perceived each other as rival gang members, and the teenage suspect made a spontaneous decision to open fire in the middle of the very crowded breezeway of the shopping mall.

"It seemed like it all developed awfully quickly," Joseph said, per Bay Area News Group. "I don’t think there could have been a whole lot of interaction between them before the shooting."

The shooting, which occurred on the second floor of the mall near the Macy's store, reportedly left three people injured, including a 16-year-old girl who was an innocent bystander. Another adult female bystander was also shot, and so was the adult male who engaged somehow with the suspect.

All three victims were hospitalized with non-life-threatening injuries.

One witness named Armando described the scene to KPIX, saying, "We all started running, and then we came to the parking lot. Everybody was running, screaming, and crying. Probably like 20 minutes after, we see a guy walk out with a wound on his chest, and he was bleeding. That’s when we knew this was real."

Police were quick to clarify that this was not a random mass shooting or active-shooter incident, but an isolated, likely gang-related altercation.

Chief Joseph said in a statement over the weekend, "A single violent act won’t define this community or this city. Today, Valley Fair is alive again with families shopping, friends gathering, and officers standing watch to ensure everyone feels safe." Joseph added that police had increased patrols at the mall.

Another gang-related incident involving teenagers at a San Jose mall occurred on Valentine's Day this year, at Santa Row. In that incident, five teen suspects were arrested, ranging in age from 13 to 18, in connection with the fatal stabbing of a 15-year-old boy in what appears to have been a case of mistaken gang-affiliation.

David Gutierrez was at the mall with his girlfriend celebrating the holiday and was wearing a red jacket for the occasion, the girlfriend told authorities, which the group of boys mistook for their rival gang's color. A 13-year-old boy is suspected of committing the stabbing and has not yet been tried. The first of the five suspects, a 16-year-old, was sentenced in August to two years home detention.

Gutierrez's family has been arguing for harsher sentences for the juvenile suspects in the case.

And at the news conference Monday, Chief Joseph seemed to give credence to those arguments, suggesting that the juvenile justice system was "broken."

"I’m not sure what tragedy will finally be the watershed moment when we fix what is clearly broken," Joseph said, referring to this shooting and the February stabbing.

DA Rosen said that his office was reviewing charges against both the 17-year-old and the 21-year-old woman who accompanied him and allegedly aided in his escape. The woman was reportedly pushing a child in a stroller at the time of the incident.

"We will be filing serious charges against at least two of the individuals, including the shooter," Rosen said, per the news group. "Please be assured that these defendants, including the juvenile who is on probation for carrying a concealed weapon, will be held strictly and severely accountable … I hope as we do our work to keep our community safe that Valley Fair will go right back to being a happy place where kids can meet Santa Claus."

Previously: Three Shot, Including Two Bystanders, In Likely Gang-Related Incident at South Bay’s Valley Fair Mall

This story has been updated throughout.