Those killed ranged in age from 26 to 60, with stories of their loved ones' heartbreak just as varied.
There was an employee of the San Bernardino environmental health department who left behind six children. An easygoing 27-year-old woman with sparkling eyes and a quick smile. A new father who was about to go on a trip to Disneyland with his young daughter.
Here are the people killed and what we know about them:
Adams, a father of one, was a prankster who loved his family. He was planning on taking his daughter to Disneyland the week after the massacre.
Adams met his wife, Summer, at church more than two decades ago when they were teenagers.
"Anyone that ever met Robert would say that he had an excellent sense of humor," she told CNN's Anderson Cooper.
The couple married 15 years ago and had their daughter, Savannah, while they were in their late 30s.
"I'm so grateful ... I have a piece of him that will always be in my life," she said. "She looks just like him. And he loved her more than anything on Earth."
She wants her husband to be remembered as someone who was positive, generous, helpful and loved everyone.
"The biggest heart ever," she said.
Adams was 40.
Daniel Kaufman worked at a coffee shop at the site of the shooting, and he had a larger-than-life personality.
He was the kind of man who chatted up strangers in checkout lines at grocery stores, said his boyfriend, Ryan Reyes.
"The man could have a 30-minute conversation with a cashier about his cats ... and I would literally have to pull him away," he said.
"One of those guys that everybody loved, got along with everybody, the life of the party, always funny, always creative."
Kaufman was 42.
The mother of three moved to the United States from Iran to escape religious persecution.
Bennetta Betbadal first settled in New York, and she eventually moved to California with her husband, Arlen Verdehyou.
"Everything she touched bloomed," Verdehyou said. "She went above and beyond."
She was 46.
Harry Bowman grew up in Pennsylvania, and moved to California about 15 years ago, the Los Angeles Times reported
He had two daughters, the newspaper reported. It said his family wanted to protect his privacy.
He was 46.
Sierra Clayborn was vibrant and always smiling. She loved her life and her job.
"When I think of Sierra, only one word comes to mind: She was a lady," Mary Hale, manager of the apartment complex where she lived, told the Los Angeles Times.
"That's not a word I use lightly. She was a super, super lady."
In a Facebook post,
her sister, Tamishia Clayborn, said she was devastated.
"You were taken too soon," she said. "My heart is broken."
Clayborn was 27.
Juan Espinoza grew up in Mexico, and moved to California in his 20s, according to the Los Angeles Times
After putting himself through college, he got a job as an inspector for the San Bernardino County health department.
The married father of two loved his family and his job.
Espinoza was 50.
Aurora Godoy was married to her high school sweetheart. They had a 2-year-old son.
She was at the facility for a meeting when gunfire erupted.
Her husband, James Godoy, told the paper he is still in shock
and trying to process her death.
Godoy was 26.
Shannon Johnson was fun, loving and kind, his girlfriend said.
So much so, that his last gesture on Earth was one of kindness.
One of the survivors of the massacre said Johnson covered her during the shooting and was her hero
. "I got you," co-worker Denise Peraza said he told her as he shielded her from bullets.
"He loved people. He loved telling stories," his girlfriend Mandy Pifer said.
She said the first thing that went through her mind when she learned of Johnson's death was how lucky she was to have had him in her life.
"He let me know that he loved me very much," she said.
Johnson rose before dawn each day to travel more than 60 miles between the Los Angeles home he shared with his girlfriend and his San Bernardino office, according to a statement from the Los Angeles mayor's office.
But there was more, so much more to him, his family said Friday.
"Shannon was a generous, fun-loving soul, who very much loved his family and friends. Shannon was a protector to all of those he loved. Shannon was friendly and easy to know, making friends everywhere he traveled," his family said in a statement.
He loved going for walks, attending concerts and "hanging out at his favorite tattoo parlor," the family wrote.
He was 45.
Damian Meins worked at the environmental health services agency. He also loved dressing up as Santa to the delight of children at a local school.
"He was an amazing guy, we'll all miss him," former co-worker Dottie Merki told The Press-Enterprise.
Meins was a graduate of Notre Dame High School in Los Angeles, where the football team put his initials on their helmets Friday night.
"Damian loved Notre Dame, and often volunteered time with us as a member of the football team 'Chain Gang,' " the school said in a statement. "His death has affected our community deeply. He will be missed."
He was 58.
Tin Nguyen was part of a big extended family that met every Sunday for dinner, the Los Angeles Times reported.
Now her seat is empty.
Nguyen's parents fled Vietnam when she was a child, and she was part of a close-knit family, the paper said.
She was on the verge of becoming engaged, her family told the paper.
Nguyen's "heart was bigger than the sun," her friend Kim Oanh Pham wrote on an online fundraiser page for funeral and other expenses.
"You couldn't help but fall in love with her addicting personality."
Nguyen was 31.
Nicholas Thalasinos was passionate about his beliefs, a friend said.
So much so, Thalasinos had a "heated, passionate conversation" about politics and religion with the gunman days before the shooting, Kuuleme Stephens said.
Stephens said that a few days earlier, she had called Thalasinos when he was in the middle of a conversation with the man later identified as the gunman. She described the talk as "calm and collected."
After reports of the shooting emerged, Thalasinos' wife said she hoped for a miracle.
"The waiting was excruciating, because you're trying to hold out hope," Jennifer Thalasinos told CNN affiliate KTLA-TV.
He didn't make it out alive.
Thalasinos was 52.
Yvette Velasco had sparkling eyes and an easy, contagious smile.
"She was a bright young girl who showed a caring heart to everyone," colleague Omar Bashir said. "She worked hard and never gave up on her dream."
Devastated relatives said they are "still processing this nightmare."
"Yvette was an intelligent, motivated, and beautiful young woman, who was full of life and loved by all who knew her," her family said in a statement.
She left behind her parents and three sisters.
She was 27.
Michael Wetzel's wife, Renee, described the father of six as "the most amazing person" she knew.
"He was her best friend. He was an amazing father and was loved by all," said Celia Behar, a friend who spoke on behalf of the family.
Wetzel worked for the San Bernardino environmental health department.
"Everyone who knew him just adored him," Behar said.
He was 37.
Isaac Amanios left Eritrea 15 years ago in search of a better life in California, the Los Angeles Times reported.
He loved his new life in his new country, where he worked as a supervising environmental health specialist and doted on his two sons and one daughter.
New York Giants football player Nat Berhe said the two are cousins, and his family is at a loss.
"My cousin's name is Isaac Amanios and he was a great human being," Berhe tweeted.
Amanios was 60.