BOULDER, Colo. (NewsNation Now) — The suspect in the Colorado supermarket shootings bought a firearm at a local gun store after passing a background check, and he also had a second weapon with him that he didn’t use in the attack that killed 10 people this week, authorities and the gun store owner said Friday.

Investigators are working to determine the motive for the shooting, but they don’t know yet why the suspect chose the store in Boulder or what led him to carry out the rampage, Police Chief Maris Herold said at a news conference.

“Like the rest of the community, we too want to know why — why that King Soopers, why Boulder, why Monday,” Herold said. “Unfortunately, at this time, we still don’t have those answers.”

Boulder County District Attorney Michael Dougherty said the quick response by officers kept others inside the store out of danger, but he declined to say how many people were there.

Investigators have an idea of how many shots were fired in the gunbattle between officers and the suspect, but aren’t revealing it yet, Dougherty said. The officer who was the first on scene was killed.

“Their actions saved other civilians from being killed,” Dougherty said about the officers. “They charged into the store and immediately faced a very significant amount of gunfire from the shooter, who at first they were unable to locate.”

More charges will be filed against the suspect, 21-year-old Ahmad Al Aliwi Alissa, in the coming weeks in connection with the shots fired at officers, Dougherty said.

John Mark Eagleton, owner of Eagles Nest Armory in the Denver suburb of Arvada, said in a statement that his store was cooperating with authorities as they investigate. The suspect passed a background check conducted by the Colorado Bureau of Investigation before purchasing a gun, Eagleton said.

Authorities previously said Alissa purchased a AR-15-style gun on on March 16, six days before using it in the shooting. The other weapon the attacker had was a 9 mm handgun.

“We are absolutely shocked by what happened and our hearts are broken for the victims and families that are left behind. Ensuring every sale that occurs at our shop is lawful, has always been and will always remain the highest priority for our business,” Eagleton said in the statement.

Alissa was convicted in 2018 of misdemeanor assault after he knocked a fellow high school student to the floor, climbed on top of him and punched him in the head several times, according to police documents. He was sentenced to probation and community service.

Colorado has a universal background check law covering almost all gun sales, but misdemeanor convictions generally do not prevent people from purchasing weapons. If Alissa had been convicted of a felony, his gun purchase would have been prohibited under federal law.

An arrest affidavit said Alissa bought a Ruger AR-556 pistol, which resembles an AR-15 rifle with a slightly shorter stock.

Alissa, who lived in Arvada, was born in Syria in 1999, came to the U.S. as a toddler and later became a U.S. citizen, according to two law enforcement officials. He would need to be a citizen to buy a gun. The officials were not authorized to speak publicly and spoke to The Associated Press on condition of anonymity.

Dougherty, the district attorney, said Friday that the FBI and other agencies were looking into the background of Alissa and the victims and didn’t yet have information to share.

The AR-15-style gun was recovered inside the supermarket and is believed to have been used in the attack, said a law enforcement official briefed on the shooting who was not authorized to speak publicly and spoke to the AP on condition of anonymity.

Alissa made his first court appearance Thursday, where his public defender asked for the mental health evaluation but provided no details about Alissa’s mental health. He is charged with 10 counts of first-degree murder and one count of attempted murder over shots fired at a police officer who was not hurt.

Alissa entered court in a wheelchair, presumably because of a gunshot wound to the leg he got in the gunbattle with police. He was last seen handcuffed and being led out of the supermarket by police Monday. He had removed all clothing except his shorts before being taken into custody, and his leg was bloody.

A rifle, a green tactical vest and a handgun were recovered inside the store, according to the arrest affidavit.

Alissa was treated at a hospital before police transferred him to jail. He has since been moved to a jail outside Boulder County due to safety concerns stemming from threats made against him, county sheriff’s spokeswoman Carrie Haverfield said in a statement Friday.

Alissa is jailed without bail and has not entered a plea, which will come later. His next court hearing will not be scheduled for two to three months to allow his attorneys to evaluate his mental state and evidence collected by investigators.

Officer Eric Talley’s funeral has been scheduled for Tuesday in the city of Lafayette. Talley, 51, who joined the Police Department in 2010, had seven children.

Remembering the victims

On Thursday night, about 2,000 people gathered for a vigil honoring the 10 victims after attorneys for the shooting suspect asked during his first court appearance that he receive a mental health evaluation before the case against him proceeds.

The memorial at Fairview High School, a half-mile from the scene of the shooting at a King Soopers supermarket, emphasized remembrance and healing. The crowd said aloud the names of those slain this week in Boulder after one resident read the names of the eight people killed in a mass shooting in Georgia just days earlier.

Many held candles and roses while locking arms or embracing each other near the base of the snow-covered Rocky Mountain foothills. After a singer led the crowd in “Amazing Grace,” Nicole LiaBraaten, a local leader of the gun-control group Moms Demand Action, asked people to “take a healing breath.”

“Our hearts are broken, and our festering wounds are split open once again. And this time it’s for the whole world to see,” said Liabraaten, whose group helped organize the vigil.

Democratic U.S. Rep. Joe Neguse, whose district includes Boulder, told the crowd no words could describe how he felt when he heard about the shooting.

“Ten lives. Ten precious lives lost too soon and remembered by so many,” he said.

Neguse said he had spoken with some of his colleagues about how to curb gun violence. “It does not have to be this way,” he said, prompting cheers.

One woman yelled, “Ban assault weapons.” That prompted another woman to scold her for not showing respect. “This is about people who died,” she said. “This is a memorial.”

Boulder officer, 51-year-old Eric Talley, was among those killed. His funeral was set for next Tuesday.

All reporting in this article from The Associated Press.