CHELSEA — The first sign of trouble came in a phone call.

A group of gang members were in Chelsea’s Bosson Playground at about 8:30 p.m. Wednesday when, a prosecutor said, one of them took a call and learned a rival gang member named Pumba was headed to the area and wanted to fight.

A short time later, a white vehicle pulled up and Pumba got out and started shooting, a prosecutor said Friday.

Six to eight shots later, the crowd had escaped harm, but inside a neighboring apartment building, 13-year-old Juan Lopez Delgado had just taken a bullet to his left shoulder, officials said.

Authorities later identified Pumba as 19-year-old Christian Garcia of Everett and arrested him Thursday evening on Interstate 93 in Lawrence. He was arraigned Friday in Chelsea District Court, where a prosecutor identified him as a gang member.

In an interview at his home after the court proceeding, Lopez Delgado said Garcia used to hang out in his neighborhood on Bellingham Street.

“He used to, like, chill in front of our house when we first moved out here. We talked and all that,’’ said Lopez Delgado, who was recuperating at home after being released from Massachusetts General Hospital Thursday evening. The bullet remains lodged in his shoulder, he said, because doctors don’t want to operate until swelling in the area subsides.

A police report said Lopez Delgado told investigators that Garcia has a dispute with the boy’s cousin and approached Lopez Delgado one or two months ago when he was looking for the cousin. But in an interview with the Globe, Lopez Delgado said he misspoke while talking to police; the man engaged in the dispute with his cousin is Garcia’s friend, he said.

On Wednesday night, the teenager said, he was watching the wrestling show “Total Bellas’’ from his bed on the third floor when he heard gunshots.

“When I heard the third one, I went up to run to my mom’s room and right there the bullet just hit me. It had so much power that I dropped to the floor,’’ said Lopez Delgado, who is in the eighth grade.

“I ran to my mom’s room and right there I just fainted, and I dropped down,’’ he said. “I said, ‘I got shot! I got shot!’ ’’

Garcia stood out of view of the courtroom during much of his arraignment. Not-guilty pleas were entered on his behalf to charges including assault and battery with a dangerous weapon and assault by means of a firearm.

Judge Ina Howard-Hogan ordered Garcia held on $100,000 bail and revoked his bail on a pending matter in Malden District Court, where he is accused of assaulting an Everett police officer.

In that incident, Garcia was accused of pushing his back and shoulder into the chest of an officer who was performing a pat frisk on him in October 2015, a police report said.

Garcia was identified as the gunman in the Chelsea shooting after a witness picked him out of a photo array, said Suffolk Assistant District Attorney Vincent DeMore.

After Garcia was taken into custody, DeMore said police seized his clothing. His family then provided Garcia with replacement clothing, which was searched by investigators, who found a shell casing in the garments, DeMore said.

Defense attorney John C. Hayes suggested in court that the case against Garcia is weak.

“This comes down right now to one [identification], one witness claiming that Mr. Garcia is the person who’s the shooter,’’ Hayes said. “That’s a very triable case if that’s all they have.’’

He said Garcia was involved with Roca, Inc., a program that aims to reduce youth incarceration. Several Roca representatives attended the arraignment.

Garcia has been linked with the group for about 2½ years, said Yotam Zeira, Roca’s director of external affairs. He said Garcia has received help with education, employment, and life skills, but declined to provide specifics.

“Roca chose as its mission to work with young men who are at the highest risk of incarceration, and all of our research shows for the intervention to be effective, you have to stay with people for a long time,’’ said Zeira. “I think you have to realize that no intervention is magic. Nothing happens overnight.’’

Lopez Delgado said he is spending his time at home taking his medications and playing Xbox.

His middle school on the North Shore sent him pizza, a basketball, and a Boston Celtics T-shirt featuring the jersey number for Jaylen Brown, who was drafted this year.

Lopez Delgado, who plays point guard, said it will be eight months to a year before he is back on the court.

“It’s a waste of my career,’’ he said glumly. “I understand. Even NBA people, they go through stuff like that too.’’

Laura Crimaldi can be reached at laura.crimaldi@globe.com.