Their lives were cut short on a Saturday at the mall, two co-workers in their 20s who were just getting started.

Brianna Benlolo, 21, had a 2-year-old son she loved and doted on. Tyler Johnson, 25, had turned his life around and mentored those struggling with substance abuse.

Both were working at the Mall in Columbia, Md., on a seemingly ordinary January morning when a gunman opened fire in the second-floor clothing store where they worked. Terrified shoppers ran for cover. The gunman, identified Sunday as Darion Marcus Aguilar, took his own life, police said.

But he killed Benlolo and Johnson first, police said, and on Sunday, investigators were still working to figure out why. Police said they had found no connection between Aguilar and the victims.

Relatives and friends of the co-workers at Zumiez — a store popular with skateboarders and snowboarders — grieved Sunday at the enormity of the loss. Johnson was a sales associate, and Benlolo was first assistant manager.

In Mount Airy, Md., where Johnson’s family was gathered, his aunt spoke briefly by phone about her nephew, whom she described as “a kind, caring person.”

“We lost a real good guy,” Maggie Sliker said.

Sliker said her nephew had been through tough times earlier in life but had been clear of drugs and alcohol for two years and now worked with others who needed support. He was on the board of the Serenity Center, a 12-step program-meeting house in Columbia.

“He was in every way going forward and rising up to become a person with a mission statement,” she said.

At the Serenity Center, its president, Stephen Sprecher, said Johnson made a difference.

“I thought he was a remarkable young man,” Sprecher said. “I don’t see a lot of young people stepping up like that. I just thought he was an up-and-coming leader.”

Johnson had a wry sense of humor, he said, and a way of reaching people young and old. “Everyone connected with him,” he said.

Paige Kendrix, a friend in Columbia, recalled that Johnson was a regular speaker to youth groups, urging teenagers to avoid substance abuse.

“He let them know they didn’t have to go down the road he did, and he was living proof of it,” she said.

Kendrix said Johnson was interested in furthering his education to make a career out of counseling young people. “He was really sweet,” she said. “If anybody didn’t deserve this, it was him.”

Claudia Friend, executive director of the Serenity Center, recalled Johnson as so committed that she knew little about his other job. Johnson’s girlfriend also was active at the center, she said. “He was very joyful. He was very handsome. He had a radiance,” Friend said of Johnson.

“I would say he was breathing and eating this recovery and spending every free moment on it. He was very dedicated to newcomers, anyone with an addiction, to help them get sobriety and abstinence,” she said.

At a vigil in Columbia on Sunday night, Franklin Goodridge told about 50 mourners that he wanted people to know that Johnson was loved by many.

“This is just not some random human — his life touched my heart,” Goodridge said. “He had the greatest smile, he had the best hair and he was a caring person. I’m still in shock.”

Four years younger than Johnson, Benlolo had graduated from high school in 2010 and moved to Maryland afterward.

Preecha Glinsong said he met Benlolo in December 2012, when she started attending Hair Expressions Academy, a beauty school in Rockville. She dropped out after a couple of months, saying it was difficult to fit school into her schedule between caring for her son, Elijah, and holding down a full-time job.

“All I know is she’s a nice girl,” he said. “She talked about how much she loves her son and would do anything for him.”

Destiney Dunn, who also works at the mall, said Benlolo was “really proud of her job.”

“She shouldn’t have died,” said a sobbing Dunn as she held a candle at the vigil.

Benlolo lived in College Park with several housemates at the edge of the University of Maryland campus. In her room were children’s books, including “Goodnight Moon.”

Friends described a sense of joy about her and said she often seemed to be smiling or laughing. “She never seemed like she had any negativity,” said Corey Lewis, a housemate.

Benlolo left behind a notebook she had filled with fanciful drawings and phrases from pop culture. One page, meticulously written in small, even, red letters, is a series of lyrics and television shows that apparently struck her fancy, such as “House of Cards,” “Kiss Me Again” and “Hearts Burst Into Fire.”

On another page, she sketched an elephant carried aloft by a balloon. And on another was a very practical shopping list that included a vacuum, a coffee table, black sweaters and baby toys.

Benlolo’s Facebook page shows a series of photos of her getting tattooed just below the clavicle. The tattoo is a large, heart-shaped lock with wings below the words “Forgive Love Live.”

The job at Zumiez was her first since giving birth, her grandfather, John Feins, told the Associated Press.

The chain store said Sunday that when the mall reopens, people will be invited to sign memory books and float flowers in the mall fountain to honor Benlolo and Johnson’s lives. While the mall is slated to reopen at 1 p.m. Monday, Zumiez plans to remain closed, Howard County police said Sunday.

“It’s senseless. It’s totally, totally senseless,” Feins told the AP. He said his granddaughter is part of a military family that had moved often. Before Maryland, they had lived in Florida and Colorado.

Feins described his granddaughter’s relationship with her son’s father as good and said the two shared custody.

“I mean, what can you say?” he said. “You go to work and make a dollar, and you got some idiot coming in and blowing people away.”

Alice Crites, Jennifer Jenkins, Dan Morse, Victoria St. Martin, Ian Shapira, Matt Zapotosky and Julie Zauzmer contributed to this report.

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