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The gunman in the mass shooting at a bar in Thousand Oaks entered the building and opened fire, tossed multiple smoke grenades to sow chaos and then sat in wait to ambush responding law enforcement officers, officials said on Tuesday.

Ian David Long, a Marine veteran who served in Afghanistan, fired a total of more than 50 rounds in the shooting at Borderline Bar & Grill on the evening of Nov. 7, Ventura County Sheriff Bill Ayub said.

Ayub’s comments Tuesday provide more details on how the gunman carried out the shooting that left 12 people dead — not including Long, who died of an apparent self-inflicted gunshot wound.

But officials said they still do not know his motive for the attack.

“We are no closer to determining that today as we were at the onset of the incident,” said Ayub.

The gunman used a Glock .45-caliber semi-automatic pistol, which he legally purchased in August 2016 in Simi Valley, Ayub said. He also had a folding knife in his possession.

The gunman brought seven high-capacity magazines to the bar, and five were still loaded when he took his own life at the end of the mass shooting, Ayub said. High-capacity magazines are illegal in California, although they are available for purchase in neighboring states.

Long had a flashlight with a laser sight attached to his handgun, and he threw multiple smoke grenades into the bar to create chaos and confusion inside, Ayub said.

After the initial shooting, he positioned himself in anticipation of the police response, Ayub said. When officers entered, he ambushed them immediately from a position of tactical advantage. The officers returned fire but did not strike him, and then retreated from the scene and waited for SWAT and other negotiating experts, Ayub said.

In all, he struck 13 people with gunfire in the shooting, including Ventura County Sgt. Ron Helus, and only one of those survived.

All of the 12 victims of the Borderline Bar & Grill shooting died rapidly from one or more gunshot wounds, according to Ventura County Medical Examiner Dr. Christopher Young. He said they were shot in vital areas, at close proximity and had no chance of survival. One victim had a stab wound to the neck in addition to the gunshot wound.

Ayub also provided further details on an April 2018 incident in which law enforcement responded to Long’s home in nearby Newbury Park. Sheriff’s deputies responded after neighbors called about a disturbance.

They heard loud noises and believed Long suffered a mental breakdown. Deputies contacted Long, who said he was upset over a financial dispute with his mother. She confirmed the dispute was related to money.

Deputies and a mental health crisis team evaluated Long and decided he did not meet the criteria for a welfare and institution hold. During this incident, no gun was displayed, no one was threatened with a gun, no one mentioned a gun, therefore a gun violence restraining order was not considered relevant.