A gunman opened fire Wednesday at the Borderline Bar & Grill in Thousand Oaks, California, killing 12 people.
The popular establishment hosts "College Country Night" on Wednesdays, and it was full of young people that evening.
An additional 23 individuals were injured and released after receiving treatment at local hospitals, according to the Ventura County Sheriff's Office.
"They are just kids," an eyewitness who identified himself as Tim told ABC 7, struggling to hold back sobs. "They're all young. This shouldn't have happened to them."
According to records maintained by the Gun Violence Archive, this latest tragedy was the 307th mass shooting this year.
These are the victims:
Sheriff's Sgt. Ron Helus
Ron Helus, 54, a sergeant in the Ventura County Sheriff's Office, was among the first to respond to the shooting, heading into the bar as the bullets flew. The veteran officer, who was married with an adult son, had been on the force 29 years and planned to retire within the next year.
Helus also owned a firearms training business.
"When he heard the gunfire, he ran in. He ran in and no doubt saved others," Ventura County Sheriff's Capt. Garo Kuredjian told CNN afterward. "That's what cops do. That's what he did."
Cody Coffman had just celebrated his 22nd birthday and was planning to join the military, his father told reporters on Thursday.
"Oh, Cody. I love you, son," Jason Coffman said through sobs, leaning on his father-in-law. "This is going to be an absolutely heart-wrenching time for me and for my family. ... For me, this is a heart that I'll never get back."
Jason remembered his son as a talented baseball player in high school and a fishing buddy "who would come with me whether he wanted to or not."
"I cannot believe it has happened to my family," he said. "I am speechless and heartbroken."
Cody was "the big brother that my kids need," the grieving father said. "I have a daughter coming on 29 of this month. He was so excited to have his first sister and now she'll never know him."
The last thing he said to Cody was a warning not to drink and drive, and then this: "Son, I love you."
Justin Meek, 23, graduated from California Lutheran University in May, where he sang the national anthem as a member of a quartet.
Meek worked as a bouncer at Borderline, a family friend told 10News, reportedly breaking windows at the bar to help people escape as the violence unfolded.
His alma mater confirmed the news of his death in an email to the community Thursday:
"The Cal Lutheran community is filled with sorrow over the violent events that took place last night a few miles from campus in Thousand Oaks," the statement read. "Sadly, we have learned from the family that a recent graduate, Justin Meek, 23, is one of the precious lives cut short in this tragedy. Meek heroically saved lives in the incident."
"Cal Lutheran wraps its arms around the Meek family and other families, and around every member of this community of caring."
Alaina Housley, 18, was at the bar along with a group of around 20 other Pepperdine students at the time of the shooting. Witnesses told Pepperdine's student newspaper, the Pepperdine Graphic, she was last seen on the dance floor.
A woman who identified herself as Housley's roommate pled early Thursday morning for information on her whereabouts:
Housley's aunt, actress Tamera Mowry, confirmed Housley's death in a statement Thursday afternoon:
"We just learned that our niece Alaina was one of the victims of last night's shooting at Borderline bar in Thousand Oaks," the actress and her husband, Adam Housley, said in a statement to BuzzFeed News. "Alaina was an incredible young woman with so much life ahead of her and we are devastated that her life was cut short in this manner. We thank everyone for your prayers and ask for privacy at this time."
This is a developing story. Check back for updates.