"This doesn't happen anywhere else on planet Earth".
Dean said in the news conference that some people who tried to escape the chaos by breaking windows might have been injured.
The massacre was the deadliest mass shooting in the US since 17 students and teachers were slain at a Parkland, Florida, high school nine months ago. Witnesses said the shots sounded like they were coming from a semi-automatic weapon.
Tributes have poured in for the sheriff's sergeant killed during a mass shooting at a country music bar in Southern California last night. He said he thought their injuries were minor, and that majority were likely injured as they escaped, some by breaking windows.
"It's a horrific scene in there, there is blood everywhere and the suspect is part of that, and I didn't want to get that close and disturb the scene and possibly disturb the investigation", he said, adding that the motive is still unclear. It's unclear whether the magazine was legally purchased.
At least 13 people were shot, including a sheriff's deputy, during the incident at the Borderline Bar and Grill.
Three of the deadliest mass shootings in United States modern history have occurred since October 2017.
Wearing a black jacket and sunglasses, the suspect shot a security guard and young female cashier before showering the Borderline bar in Thousand Oaks near Los Angeles with bullets.
Long was found dead in the Borderline Bar and Grill after 12 people were shot to death late on Wednesday. The 28-year-old was on active duty with the marines from August 2008 to March 2013, CNN reported, citing the Department of Defense.More news: Melbourne Cup 'tragedy' as horse reportedly put down
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Ventura County Sheriff Geoff Dean added of his former colleague: "He was totally committed, he gave his all, and tonight, as I told his wife, he died a hero".
"Hey, I got to go handle a call, I love you", Helus told his wife, according to Dean.
Officials have not released the names of all the victims as they worked to notify the families. Once safely outside, the uninjured hugged and awaited word about those still inside. He died in an area hospital Thursday morning.
"We don't know who shot anybody at this point". Coffman told reporters later Thursday that his son just wanted to be a good big brother to his siblings. Authorities believed Long then turned the gun on himself. He was a machine gunner. Long served in the Marine Corps from August 2008 to March 2013, with a deployment in Afghanistan between November 2010 and June 2011, military records show.
"Stop the words of hate", Myers said at a memorial in Pittsburgh the day after the shooting.
"He [reloaded] in about six seconds, which is really fast, so he knew what he was doing", she told reporters.
A witness told KABC-TV that there were many young people "having a great time" in the bar when a man entered and "started shooting". However, mental health specialists who were called in "talked to him, and cleared him".
But when Helus and a California Highway Patrol officer entered the bar about 11:20 p.m., gunshots were already piercing the room. That Sheriff's Sergeant died in the hospital. "God bless all of the victims and families of the victims". "Thank you to Law Enforcement", the president said in another tweet.
This is a developing story and will be updated.