ImageThe Thousand Oaks Victims: A Student, a Deputy, a Would-Be Soldier
A vigil for those killed in a shooting at Borderline Bar & Grill was held at Alliance of the Arts in Thousand Oaks, Calif., on Thursday night.CreditCreditJenna Schoenefeld for The New York Times

When a gunman opened fire at the Borderline Bar & Grill in Thousand Oaks, Calif., on Wednesday night, a chaotic scene unfolded. People ran. Some dropped to the dance floor. Some hid, others fled from the building.

Killed in the gunfire were 12 people, including a longtime sheriff’s deputy who had rushed into the crowded bar to help and a 22-year-old patron whose friends said he had tried to help others escape, yelling “Everyone, run!” There was a college freshman who wanted to major in English literature, and a recent graduate who had collected his degree in criminal justice in May.

These are the stories of some of the people who died in the attack.

This article will be updated.

ImageThe Thousand Oaks Victims: A Student, a Deputy, a Would-Be Soldier
Sean Adler

Sean Adler, 48, had been a coach with a high school wrestling team in Simi Valley, Calif., but had recently changed careers. This year he opened a coffee shop called Rivalry Roasters, realizing a long-held dream, one of his childhood friends said. He was also holding down a job as a bouncer at the Borderline Bar & Grill, Royal High School’s wrestling team said.

Mr. Adler’s death was confirmed on Thursday by his sister. Chris Curtis, the co-owner of Rivalry Roasters, said Mr. Adler had children and had been working at the bar to help pay the bills.

Danny Evans, one of Mr. Adler’s childhood best friends, said that although he had not spoken to Mr. Adler recently, he recalled that in high school, his friend “was the guy we all wanted to be: handsome, athletic and kind.”

“When we were younger, I was an awkward kid,” Mr. Evans said. “I got picked on.”

“And Sean was my protector,” he continued, choking back tears. “He stood up for me, and he showed me the kind of kindnesses I didn’t get from other people. I needed that so badly at that time.”

“I’m so proud to have been his friend,” he added. “It’s devastating that he’s gone.”

ImageThe Thousand Oaks Victims: A Student, a Deputy, a Would-Be Soldier
Cody Coffman

Cody Coffman, of Camarillo, Calif., had just turned 22 and was planning to join the Army, said his father, Jason Coffman, who confirmed his son’s death in an interview with reporters that aired on CNN.

A friend, Sarah DeSon, 19, said she believed she survived the shooting because of Mr. Coffman’s quick reaction. “He was protecting everyone,” Ms. DeSon said. “He got up and he just yelled, ‘Everyone, run!’”

Baseball was Mr. Coffman’s passion. He played on his high school team and served as an umpire. He liked spending time with his younger siblings and often went fishing with his father.

“I talked to him last night before he headed out the door,” Jason Coffman said in the interview outside the Thousand Oaks Teen Center, where families had gathered to await information. “First thing I said was, ‘Please don’t drink and drive.’ The last thing I said was, ‘Son, I love you.’”

ImageThe Thousand Oaks Victims: A Student, a Deputy, a Would-Be Soldier
Sgt. Ron Helus

Members of the Ventura County Sheriff’s Office said the death toll might have been higher if not for Sgt. Ron Helus. As the shooting unfolded, Sergeant Helus ran inside.

“He went in to save lives, to save other people,” Sheriff Geoff Dean said. Before entering the bar, the sheriff said, Sergeant Helus had a conversation with his wife on the phone.

Sgt. Eric Buschow told CNN: “I don’t think there is anything more heroic than what he did.”

Sergeant Buschow described Sergeant Helus as “a true cop’s cop.” In 29 years on the force, he worked in various departments, including narcotics and SWAT, his colleague remembered.

“He had a natural instinct going after crooks,” Sergeant Buschow said. “He did it with enthusiasm and a great deal of intelligence.”

Sergeant Helus, 54, had been set to retire this year.

He loved being outdoors and fishing with his son in the Sierra Nevada. On his LinkedIn page, he said that in addition to his policing job, he owned a firearms safety training business called Gun Control.

Expressing condolences for those who died in the shooting, Gov. Jerry Brown singled out Sergeant Helus, who he said “took heroic action to save lives last night.”

On Thursday morning, as Sergeant Helus’s body was taken from a hospital to the county medical examiner’s office, members of the sheriff’s office accompanied him in a solemn procession.

ImageThe Thousand Oaks Victims: A Student, a Deputy, a Would-Be Soldier
Alaina Housley

Alaina Housley, a freshman at Pepperdine University, loved music and soccer.

Ms. Housley, 18, of Napa, Calif., was a graduate of Vintage High School. She had written on Facebook that she planned to major in English literature. She also said she hoped to be accepted into a vocal music program.

Photos on social media showed that she had been a member of her high school choir and performed in a production of “Les Misérables.” She was also involved in an organization, Helping to Introduce Opportunities, that donated soccer gear to young people in the developing world.

Her uncle and aunt, Adam Housley and Tamera Mowry-Housley, confirmed her death in a statement issued by their representatives. On Twitter, Mr. Housley called her a “beautiful soul.”

After Pepperdine’s family and alumni weekend last month, Ms. Housley posted on Instagram “finally got to see my parents” — with two pink hearts.

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At least 12 people were killed in a shooting late Wednesday at a bar in Thousand Oaks, Calif. Borderline Bar and Grill was holding its weekly event for college students.Published OnCreditCreditJenna Schoenefeld for The New York Times

Daniel Manrique was a Marine Corps veteran who never stopped working to support other men and women who had served in the United States military.

He worked as a program manager for Team RWB, a veterans’ support organization, which confirmed on Thursday that he had died at Borderline the night before.

In a statement, the organization added that Mr. Manrique had served as a radio operator with the 2nd Combat Engineer Battalion, 2nd Marine Division, and deployed to the Middle East in 2007 with the 26th Marine Expeditionary Unit.

“Dan’s life was dedicated to serving others, during his military career and beyond,” said John Pinter, the executive director of Team RWB.

In a profile on the organization’s website, Mr. Manrique was described as an active member of the Los Angeles area community who enjoyed hiking, biking and photography.

On social media, he posted frequently about his activities, which included climbing a mountain to raise money for veterans, organizing a surfing trip for veterans with disabilities and going to countless sporting events. Mr. Manrique was an avid baseball fan who loved the Los Angeles Dodgers.

ImageThe Thousand Oaks Victims: A Student, a Deputy, a Would-Be Soldier
Justin Meek

Justin Meek, 23, graduated from California Lutheran University in May with a degree in criminal justice.

His mother, Laura Lynn Meek, received a bachelor’s degree alongside her son that day, noted an article in a local paper, The Ventura County Star. She was a veteran who carried the American flag into the ceremony, the article said, while her son sang the national anthem in a quartet.

A spokeswoman for California Lutheran confirmed Mr. Meek’s death. Other students were also at the bar, said the spokeswoman, Karin Grennan, and the school had heard from those who escaped unharmed.

Mr. Meek’s Facebook cover photo showed him grinning widely, wearing overalls and a sleeveless plaid shirt, surrounded by other young people at Borderline, the bar where the shooting occurred. It was posted on Sept. 8.

The page described Mr. Meek as a performer with Goode Time Productions, a small company that produces services at weddings and parties.

Mr. Meek was also well known for the work he did for the community. As a caregiver with Channel Islands Social Services in Camarillo, Calif., he gave in-home support to families with children who had developmental disabilities.

“Justin was an exceptionally kind and gifted young man who always went out of his way to help others,” Sharon M. Francis, the chief executive of Channel Islands Social Services, said in a statement.

“He went out of his way to provide personalized care, attend their family events, birthday parties, and ensure that every moment he provided with them was meaningful, and based on their child’s interests.”

Ms. Francis added that he worked at Borderline as a promoter and a bouncer.

Mr. Meek regularly shared ads for Borderline’s College Country night. The day after the deadly shooting last year at a country music festival in Las Vegas, Mr. Meek had posted a photo of himself with the hashtag “#PRAYFORVEGAS.”

When a gunman opened fire at the Route 91 Festival in Las Vegas last year, Telemachus Orfanos somehow made it through.

It was a brutal experience, his friends thought, never to be repeated.

They were wrong.

“He was killed last night at Borderline,” Susan Orfanos, the mother of the 27-year-old, said in a phone interview on Thursday night. “He made it though Las Vegas, he came home. And he didn’t come home last night, and the two words I want you to write are: gun control. Right now — so that no one else goes through this. Can you do that? Can you do that for me? Gun control.”

Ms. Orfanos then hung up the phone.

ImageThe Thousand Oaks Victims: A Student, a Deputy, a Would-Be Soldier
Noel SparksCreditJackie Jones, via Associated Press

Noel Sparks had her hands in a little bit of everything at the church she grew up in with her family.

She was an all-around creative, said Nancy Moravec, the former director of Christian life at the United Methodist Church of Westlake Village, where she met Ms. Sparks when she was a child.

Over the years, Ms. Moravec said, she watched as Ms. Sparks got involved in just about every aspect of the church, from its youth program to the church camps she would later return to as a counselor. She sang in the choir, played the cello and danced.

“She was a beautiful dancer,” Ms. Moravec recalled.

The Rev. Walter C. Dilg Jr., the senior pastor of the church, confirmed in a telephone interview Thursday that Ms. Sparks died in the shooting. He said he had learned of her death from her parents, who are still members of the church.

Ms. Moravec, 74, described Ms. Sparks as “loving, kind and generous.” Ms. Moravec estimated that Ms. Sparks was now in her early 20s, and said she had been a student at Moorpark College.

“If you had children, you wanted Noel to be one of their friends,” she said.

Thomas Fuller, Julie Turkewitz, Matt Stevens, Jacey Fortin and Andrew R. Chow contributed reporting. Kitty Bennett and Jack Begg contributed research.