Speaking at press conference in the wee hours of Thursday, a sheriff said that around a dozen other people had been injured.
Numerous scores of young people regularly went to Borderline Bar & Grill in Thousand Oaks, California, where a gunman stormed in on Wednesday and opened fire, killing 12 people before killing himself.
The sheriff's department had several previous contacts with Long including a call to his home in April when deputies found him acting irate and irrationally.
Long had received two minor traffic citations in recent years, Dean said. He was found dead in the office of the Borderline, after reportedly having shot himself.
The venue in the quiet, upscale Thousand Oaks suburb had been hosting an event for college students, with possibly several hundred young people in attendance, Captain Garo Kuredjian of the Ventura County Sheriff's office said earlier.
Authorities did not say how the gunman died.
"It's a horrific scene in there", Dean said. "There is blood everywhere and the suspect is part of that".
What else do we know?
Helus and a California Highway Patrol officer, who hasn't been publicly named, were on scene within minutes, and were the first responders to courageous their way into the bar, darkened by a smoke bomb set off by Long.
A SWAT team from the Ventura County Sherrif's Department, arrived within minutes, along with the Federal Bureau of Investigation and other officers to find the bar strewn with bodies, survivors huddling in terror, and others desperately trying to get out.
Police say the suspect was dressed in black, and forced his way into the bar after shooting the bouncer.
President Donald Trump, who has resisted a surge in calls for tougher gun controls since 17 students were shot dead at Stoneman Douglas High School in Florida earlier this year, said on Twitter that he had been "fully briefed on the awful shooting in California".
"Great bravery shown by police", Trump tweeted. He also wrote, "God bless all of the victims and families of the victims".
Orfanos' father, Mark Orfanos, said the shooter - identified as ex-U.S.
We've got more newsletters we think you'll find interesting. "I cling to the hope that the new members of Congress will step up where their predecessors let us down".
In June 2016, 49 people were killed and more than 50 were wounded in the shooting at Pulse nightclub in Orlando. "And she looked at me through her tears and she said: 'He would have wanted it that way'". "I don't know if she is alive", he said. He was shot multiple times as he went through the front door.
"It was just aimless shooting in any direction, and he pointed and just started shooting at the crowd that I was in", Spady said. "There was probably three or four".
"I remember when I was on the ground, seeing a girl getting trampled".
Holden Harrah, who was at the bar, told CNN the gunman walked in and opened fire within seconds. The gunman was throwing smoke grenades all over the place.
"He went in there to save people and made the ultimate sacrifice", Dean said.
Many survivors said they were alive because of complete strangers who put their own bodies on the line.
Witnesses said that people dropped to the floor and hid behind bar stools in stunned silence.
"Dan's life was dedicated to serving others, during his military career and beyond", said John Pinter, Executive Director of Team RWB.
People watch as police vehicles close off the area outside a country music bar and dance hall in Thousand Oaks. Last thing I said was, "son, I love you".