WATCH: California bar massacre leaves 12 dead

WATCH: California bar massacre leaves 12 dead

Transcript for California bar massacre leaves 12 dead

where it’s now been found. Good evening from California tonight. And you probably woke up this morning like so many in this country, say ig, not again. We are here in Thousand Oaks, California, tonight, the scene of the nation’s newest mass shooting. This time, at a popular country music bar, the borderline bar and grill on college student. For students as young as 18, hundreds of people inside, when the horror and the chaos began. The shots ringing out, people hiding wherever they could, under tables and bar stool S smashing windows to get away. Carrying the injured as they ran. Police rushing to the scene, heavily armed officers, including a police sergeant who was among the first to go in, that sheriff’s sergeant did not survive. Outside, the stunned survivors looking for their missing friends. And overnight and this morning here, families, parenting rushing to the bar, some waiting for hours, waiting for news. Tonight, we have now learned 12 people did not survive. And the heartbreaking moment a father here, holding a picture of his son, then learning he’d lost him. ABC’s kayna Whitworth on the scene, she’s been here all night long, and she has the video now emerging from inside that bar tonight. Reporter: Breaking glass. An empty dance floor. As the camera shakes, that piercing sound. Gun fire. Silence. For six endless seconds. Then listen as people run for their lives. Guys, run. He’s coming out this door. Reporter: It’s 11:20 P.M. Wednesday night. Police say a gunman dressed in black started shooting before he went inside. He shot the doorman, the bouncer. Just a young man. And then he shot the cashier. Just a young girl. The subject was at the front shooting at everybody. Think he’s still inside the bar. Reporter: Witnesses say the bar quickly filled with smoke. The gunman but throwing smoke grenades. We got multiple people down. We need a lot of ambulances. Reporter: Amid the chaos, the voice of a young man calling home. Mom, dad, this is max. There’s been a shooting at borderline. Please wake up. Reporter: The gunman keeps firing. I was on the dance floor. I heard the shooter. I looked back. And then, a split second later, everybody yelled, “Get down.” Reporter: Sheriff’s sergeant Ron helus is the first on scene within minutes. They rush inside, taking on the suspect. Sergeant helus is shot several times and does not survive. 11 others also killed. Several more wounded. It’s a horrific scene in there. There is blood everywhere. Reporter: The gunman identified by authorities as 28-year-old Ian David long, a farmer marine. Authorities say it appears he took his own life inside the bar. Matt wennerstrom hid under a pool table until it was safe to run. So, I grabbed a bar stool, went through the window, and whoever was in the front, basically, was pushing the glass down and jumping out and helping the guys and girls out. And kayna Whitworth is with us live tonight. As you report there, it was college night. So many young people inside. And the sheriff today saying that those active shooter drills that so many of our young people are growing up with might have saved lives last night? Reporter: Yeah, David, it’s a sad reality. But the sheriff said, this could have been so much worse, if not for the heroes inside. This is an area surrounded by three major colleges, and students I spoke with called this their safe place.

This transcript has been automatically generated and may not be 100% accurate.

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