The Borderline Bar & Grill was packed as patrons danced, watched a Lakers’ game or played pool.
Suddenly, a man wearing a black trench coat and glasses approached the bar entrance and shot the security guard.
Inside the bar, some people thought it was fireworks or sound effects from the music, and kept dancing, witnesses said.
Within seconds, witnesses said, the gunman burst into the bar with a Glock .45-caliber handgun and shot someone at the cash register. People dropped to the ground and hid under pool tables and bar stools. Some piled atop one another while others slammed bar stools against windows to break them.
Those who got out ran, the rapid gunfire echoing around them in the dark.
“They ran out of back doors, they broke windows, they went through windows, they hid up in the attic, they hid in the bathroom,” Ventura County Sheriff Geoff Dean said.
By the time the gun went silent, 12 people were dead, including sheriff’s Sgt. Ron Helus.
Thousand Oaks, California, described as one of the nation’s safest cities, is now on the long list of places affected by a mass shooting.