Ten people were shot to death at a Colorado grocery store on Monday. The victims included a police officer who was among the first to arrive on the scene.

Eric Talley, 51, had already had a career working in the tech industry when he shifted course at age 40 and joined the Boulder Police Department.

He was as busy on patrol as he was at home, helping to raise seven children, the youngest of whom was 7 and the oldest 20. A friend recalled Officer Talley’s choice of transportation — a 15-passenger van.

He had done such a thorough job teaching his children first aid that when one of his sons swallowed a quarter, another son sprang into action, using his father-taught resuscitation skills. The police department gave the older son an award for lifesaving just a couple of weeks ago.

Officer Talley was on duty on Monday when a barrage of calls came in: Gunfire had erupted at a King Soopers grocery store. He was the first on the scene.

“The world lost a great soul,” said the officer’s father, Homer Talley, a retired optics engineer who lives near Abilene, Texas. “His family was the joy of his life.”

Like the people shopping at a Walmart store in El Paso in 2019, like those working in three Atlanta area spas last week, 10 victims in Boulder, Colo., including Officer Talley, were killed by the gunfire of a heavily armed man.

They were young and old, single and married, King Soopers customers and King Soopers employees. The youngest was 20; the oldest 65.

Some had spent years working at the grocery. Others had been in the store only a few minutes. All left behind relatives and friends who were struggling to comprehend what had happened and who were more eager to talk about how their relative or friend had lived than how they had died.

I don’t want her name to be another name next to an age on a list,” said Alexis Knutson, 22, a friend of Teri Leiker, 51, a King Soopers employee who she said had worked there for about 30 years and who died in the attack.

Employees of the King Soopers grocery store left bouquets and a note remembering coworkers who died in the shooting on Monday.
Eliza Earle for The New York Times

Ms. Knutson met Ms. Leiker through a program called Best Buddies that connects students at University of Colorado Boulder with members of the community who have intellectual and developmental disabilities. Ms. Knutson remembered going together to university sporting events, and how Ms. Leiker loved to cheer on the teams.

“She had the biggest, brightest smile,” Ms. Knutson said. “She always just had these dimples that, especially when she got excited about something — her smile was just huge.”

She worked as a bagger. If a customer tried to help her bag, she was known to cheerfully swat away their hand and say, “I’ve got this.”

Despite their age difference, Ms. Knutson said, they bonded, and would talk often. “I always had a rule: She couldn’t call before 9 a.m. because I like my sleep,” she said. “She would always call me at 6 a.m.”

Rikki Olds, another worker at King Soopers, also was killed. She had been a front-end manager at the store, where she had worked for about seven or eight years, her uncle, Robert Olds, said in an interview.

“We’re just devastated,” he said.

Ms. Olds was an energetic young woman who “brought life to the family,” her uncle said.

She was the oldest of three siblings, and had been left with her grandparents when she was a teenager, Mr. Olds said, adding that the grandparents raised her in Lafayette, Colo.

Lately, Ms. Olds had been living on her own, but she regularly stopped by her grandmother’s house to spend time with her grandmother and other relatives.

“My mom was her mom,” Mr. Olds said. “My mom raised her.”

Denny Stong, 20, worked at the store for several years. Only a few years ago, he had been a student at Fairview High School in Boulder.

One day in a hall at Fairview, he complimented a classmate, Molly Proch, on her superhero T-shirt, and the two became fast friends.

“I’ve been spending most of my morning crying, really confused on how something like this could happen again,” said Ms. Proch, 20. “He was an essential worker, working at a grocery store. It makes my blood boil.”

Theo Stroomer for The New York Times

Ms. Proch said Mr. Stong enjoyed hunting and was a strong supporter of the Second Amendment, but also supported strengthening certain gun regulations. “He was so passionate about expressing how he thought the government should handle weapons” to avoid mass shootings, she said.

Mr. Stong had recently posted on his Facebook page, encouraging friends to donate to the National Foundation for Gun Rights for his birthday.

He dreamed of becoming a pilot, working extra shifts at King Soopers to save money for plane fuel while he worked to get his pilot’s license, said Laura Spicer, whose son was Mr. Stong’s best friend.

Lynn Murray, a 62-year-old mother of two, was working on Monday, too, but not for King Soopers. Ms. Murray was there filling an Instacart order.

She had retired from working behind the scenes in the New York fashion world, her husband said. She was a former photo director for several glossy New York City-based magazines, said her husband, John Mackenzie, and the couple moved out of New York in 2002, first to Stuart, Fla., and then to Colorado, to raise their two children.

“I just want her to be remembered as just this amazing, amazing comet, spending 62 years flying across the sky,” Mr. Mackenzie said. “Our tomorrows are forever filled with a sorrow that is unimaginable.”

To her children, Olivia, 24, and Pierce, 22, Ms. Murray was a fashion expert of a different sort, with a knack for designing their Halloween costumes.

“The most undeserving person to have to be shot down I can think of has to be my mother,” Olivia Mackenzie said, “and I just wish it could have been me.”

Erika Mahoney, the daughter of another victim, Kevin Mahoney, 61, recalled on social media how he had walked her down the aisle for her marriage last summer. Ms. Mahoney, the news director for KAZU Public Radio in the Monterey, Calif., area, wrote on Twitter that she was heartbroken.

“I know he wants me to be strong for his granddaughter,” she posted, noting that she is now pregnant. “I love you forever Dad. You are always with me.”

Mr. Mahoney had worked as the chief operating officer for Stonebridge Companies, a hotel development and hospitality management company, before he left in 2014, a spokesman for Stonebridge said.

Neven Stanisic, 23, had been fixing coffee machines at the Starbucks inside the supermarket, but had left and was in the parking lot when he was gunned down, said the family’s priest, the Rev. Radovan Petrovic.

The son of Serbian refugees who had fled central Bosnia during the violence of the 1990s, Mr. Stanisic was born in the United States. His Facebook page is filled with anime drawings. His profile picture shows him in a blue cap and gown, posing with friends from his Lakewood, Colo., high school.

Eliza Earle for The New York Times

He was the shining hope, Father Petrovic said, “of a family who, like many refugees, had come with basically nothing but their lives, to start a new life here.”

After high school, Mr. Stanisic had gone straight to work repairing coffee machines throughout the Denver area with his father, Father Petrovic said.

“They fled war to save their lives, and to be struck by such a terrible tragedy — the loss is beyond comprehension.”

Neighbors knew Suzanne L. Fountain, 59, as a prolific gardener who gave away a steady stream of tomatoes, lettuce and basil over the tall wooden fence surrounding her yard in Boulder.

“She grew some amazing vegetables,” said Laura Rose Boyle Gaydos, who until recently lived next door to her. “She would always share her abundance with us.”

Ms. Fountain was particularly fond of a peach tree that she had planted, and could often be found sitting outside in the early evening, watching the sun set over the mountains. She had lived in her house for more than 20 years, raising a son and going through a divorce.

She had been an actress in the early 1990s, appearing in productions at the Denver Center for the Performing Arts, but she had given that up. In 2018, Ms. Fountain embarked on a new career, starting a business to advise people newly turned 65 about how to apply for Medicare.

Tralona Lynn “Lonna” Bartkowiak, another of the victims, was the face of Umba, a shop in Boulder that sold yoga and festival clothing. Ms. Bartkowiak, 49, managed Umba, which was launched by her sister, and she often attended Burning Man and other festivals, where she would mingle with prospective customers.

“Her people,” recalled her brother, Michael Bartkowiak. “She would always say that. ‘I love my people.’”

Ms. Bartkowiak was the eldest of four close-knit siblings. “She rented a house outside Boulder,” her brother said, “and lived there with her little Chihuahua, Opal. She had just gotten engaged. She was, you know, organic — stir fries, salads — she was always trying to be healthier.”

Ms. Bartkowiak was at the grocery store on Monday to pick up a prescription when the shooting began.

Officer Talley, who by Monday was an 11-year veteran of the Boulder Police Department, was born in Houston and raised in Albuquerque, his father said.

Not long after joining the Boulder department, he made the local paper, The Boulder Daily Camera. He was mentioned, along with two other officers, for a tricky operation — wading into a drainage ditch to rescue a trapped mother duck and 11 ducklings.

“We’re just trying to put the pieces back together,” the elder Mr. Talley said. “It was always in the back of my mind — and of his mind — that this could happen. It concerned him because he didn’t want to put his family through something like this.”

Neil MacFarquhar and Elizabeth Dias contributed reporting. Jack Begg, Susan C. Beachy and Kitty Bennett contributed research.