Twelve people, including a police officer, have been killed after a gunman opened fire in a southern California bar. He died at a hospital after being shot numerous times.
While authorities have not named all 12 victims in the shooting, a father of one person who died identified his 22-year-old son as among those who were killed.
Sheriff Geoff Dean, who is set to retire on Friday, said Long may have suffered from post-traumatic stress disorder and was known to law enforcement officials due to several unspecified "contacts" stretching back multiple years.
Carl Edgar, 24, of Tarzana said: "As far as I know, all of my friends are OK, safe".
The attack on the bar - a college favorite and was hosting a country music event - was the nation's deadliest shooting since 17 students and teachers were killed at a Parkland, Florida, high school nine months ago.
Dean said his officers had several interactions with Long, including an April call to his home. Some dived through windows while others hid in restrooms. It also came less than two weeks after a gunman massacred 11 people at a synagogue in Pittsburgh.
"We believe he shot himself", said Dean, adding that the shooter's motive was unknown. Add Thousand Oaks Shooting as an interest to stay up to date on the latest Thousand Oaks Shooting news, video, and analysis from ABC News.
In yet another unusual coincidence, one of the victims to be named in the Vegas shooting was Susan Smith from Simi Valley which is only miles from the site of the Borderline shooting.
Map of California locating shooting at a bar in Thousand Oaks.
Sgt. Ron Helus was a 29-year veteran of the police force.
Located around 40 miles west of Los Angeles, Thousand Oaks was recently ranked as one of the country's safest cities.
When authorities entered the bar later, they found Long dead inside an office next to the entrance.
Holden Harrah, a young man who saw the incident, cried as he told CNN that a place where he goes every week to have fun with friends had been a scene of carnage.
In one such video, she interviewed Tim Dominguez, who recalled escaping the bar with his son as others lost their lives around them, including a responding sheriff's deputy. She said everyone yelled "Get down!" and then it was silent for a few seconds.
She said she had planned to go with them but stayed behind to do some schoolwork instead.
Tayler Whitler, 19, said she was dancing when the gunman opened fire.