‘Sebastian was a gentle soul.’ Sixth grader killed in Andover remembered as bright light at St. John’s Prep.

Sebastian Robinson, 12, was found shot to death with his parents in their Andover home Feb. 9.St. John’s Prep

Sebastian Robinson, the 12-year-old killed in a murder-suicide in his family’s Andover home, was remembered by his teachers as a “gentle soul” who loved to play the cello and brought a relentless curiosity to his studies at his Catholic middle school.

At a prayer service at St. John’s Preparatory School, where Sebastian was in the sixth grade, educators and classmates recalled him as a youngster with a “genuine curiosity about the world around him.”

“Sebastian was a gentle soul who loved being at St. John’s Prep,” Head of School Ed Hardiman said during the Thursday evening service, which drew more than 2,000 people who filled the school’s wellness center.

“People in this room — teachers, classmates, and staff — made a difference in Sebastian’s life and brought joy to his experiences,” Hardiman said during the service, which was livestreamed on Facebook. “Whether it was his playing the cello, decorating a classroom door, vocalizing one of the string noises when his cello string broke as he rehearsed ‘Jingle Bells,’ engaging in a discussion on a piece of literature, and doing even more work than was assigned, people in this room, at this school, made sure that Sebastian knew that he was known, that he was valued, and that he was loved.”

Michael Driscoll, the middle school campus minister, read a personal remembrance of Sebastian as well as recollections from some of his grief-stricken teachers. The boy’s cello was displayed near the podium.

“Sebastian was a compassionate and caring classmate to all those around him,” Driscoll said, his voice quavering. “He would always listen and respect those who would share their thoughts. In the beginning of the year, he found the confidence to get up in front of the entire class and share his identity flag project. And from that moment, he found his place at the Prep. I know he was proud of his work that he accomplished during the year, and I will be forever grateful that I taught his kind soul.”

In words that Driscoll shared with the audience, middle school counselor Katherine Gorham recalled Sebastian as “an incredible reader,” who loved to ride his bike.

“That was what he talked about enjoying most out of school,” she wrote. “We also shared a bond over animals: He loved cats most, but enjoyed talking about and looking at pictures of all animals in general.”

Sebastian was part of a “tight-knit posse of kids, that were truly the [definition] of friendship and belonging,” she wrote, recalling that they loved to play Uno and Connect Four together. “It was incredible to see the bond blossom.”

Music teacher Diane Hastings said Sebastian was intelligent and hard-working.

“Sebastian showed purpose, determination, and humor in his studies of the cello,” Hastings wrote. “He displayed a clear aptitude for learning and was very quick to pick up new concepts and master new skills. Though reserved in class, Sebastian showed his personality on several occasions, such as when recording homework videos for cello, or when he attached a funny handwritten note to request my assistance in having his cello tuned.”

He was “a bright light” who will be “missed deeply amongst the orchestra class,” she wrote.

Classes were canceled at the school Thursday and Friday in light of the tragedy.

But students were encouraged to return to the wellness center for activities, food, and opportunities to speak with counselors.

Authorities said that Sebastian and his mother, Linda Robinson, 55, were killed early Thursday morning when his father, Andrew Robinson, 56, fatally shot them before turning the gun on himself and taking his own life.

Police said there had been no previous calls to the family home on Porter Road and did not provide a motive for the shootings.

“Domestic violence thrives in silence so, other than to the victim, it isn’t unusual for others not to know about the most private aspects of the life of someone who causes such harm,” said Debra J. Robbin, executive director of Jane Doe Inc., a Boston-based advocacy group for victims of domestic violence, in a statement.

“However, as a community, it is upon all of us to learn about” domestic violence and “understand that we all have a role to play in sharing resources, being responsible upstanders, and fostering healthy relationships.”

At the prayer service, Sebastian was remembered as a boy who was coming into his own.

“While fairly guarded early on, it seemed like every day Sebastian opened himself up more to those around him,” wrote Kevin Correa, an English and social studies teacher at the middle school, in a remembrance that Driscoll read.

“As he did, he began forging friendships and making the school his own,” Correa wrote. “When I think of Sebastian, I think of a young man with a genuine curiosity about the world around him and a love of learning for the sake of learning.”

On the school’s Facebook page, mourners recalled the boy’s talents and kindness.

“My son was a fellow classmate and said he was the nicest and smartest boy he’s met,” wrote one parent. “My heart breaks.”

Another St. John’s Prep parent, Nicole Hanlon, said her family will remember Sebastian for “talents and kindness.”

“My son spoke highly of his accomplishments in a recent writing contest and door decorations at Halloween,” Hanlon wrote. “Fly high Sebastian, you will not be forgotten by the SJP community.”

At a press conference at St. John’s campus on Thursday, Hardiman recalled how Sebastian was “extraordinarily creative” and impressed many with the door he decorated on Halloween.

”The door that he created had 3-D models, a QR code, and it had a soundtrack,” Hardiman told reporters.

Hardiman said Sebastian took part in “a number of concerts” and “a number of different activities” at St. John’s that were attended by his parents.

“Sebastian’s parents had been present at those and been part of the Prep community, and had been here to support their son,” Hardiman said.

When asked about his interactions with Sebastian’s parents, Hardiman declined to comment.

“I don’t really have much to say on that, I’m sorry,” Hardiman said.

Linda Robinson’s father, Joseph Hachey, on Thursday described Sebastian as “an angel.”

“He’s with his grandmother now,” Hachey said from his Lynn home as he picked up a photo of his wife, Claudette, who died in 2020.

Globe correspondent Claire Law contributed to this report.