ALLEN, Texas - The gunman who killed eight people at an outlet mall in suburban Dallas posted photographs of the shopping center three weeks before the attack on a social media account where he fantasized about race wars and the collapse of society.

The social media posts, the last of which went online Saturday shortly before he stormed into the shopping mall, included violent, hateful references that included singling out Asians with slurs. Mauricio Garcia, 33, also used his account on Odnoklassniki, a Russian social media platform, to reference “the noble war,” a phrase that many white supremacists use to describe their belief in an impending race war.

On Monday, as Texans grieved over the state’s second mass killing in a little more than a week, authorities largely avoided discussing a possible motive for Garcia’s rampage. But details of his background continued to trickle out, including news that he briefly received military training but was discharged from the U.S. Army over a mental health condition after three months of service.

Heather J. Hagan, an Army spokesperson, said Garcia joined the Army in June 2008 but was “terminated” three months later, failing to complete his initial training.

Garcia was separated for an unspecified mental health issue, according to another Army official, who spoke on the condition of anonymity because of the sensitive nature of personnel records.

Texas officials have offered few details about what might have prompted Garcia to launch his attack, which lasted until he was confronted by a police officer who shot and killed him. The shooting, the country’s 22nd mass killing so far this year, horrified the diverse, affluent communities that make up the northern suburbs of Dallas. The killings are also reigniting debate over whether Texas gun laws are stringent enough.

The victims include an engineer from India, a 20-year-old mall security guard, three out of four family members, and two elementary-school-age sisters.

At the Texas Capitol in Austin, the shooting reverberated in the legislature as a House committee voted to advance a bill raising the minimum age to buy certain types of firearms to 21, up from 18. But the legislation is expected to face an uphill battle on the House floor and in the state Senate.

In Washington, White House press secretary Karine Jean-Pierre reiterated calls for Congress to consider stricter gun laws nationwide.

“Schools, shopping malls, churches, movie theaters, grocery stores, temples, places that are part of our everyday lives - that are essential to our everyday lives - day after day are coming under attack from weapons of war,” she said.

Garcia walked up to Allen Premium Outlets in Allen carrying multiple weapons and had five additional guns in a vehicle in the mall’s parking lot, people familiar with the investigation told The Washington Post.

Authorities said seven people ranging in age from 5 to 61 were also wounded in the attack. Medical City Healthcare, a network of Dallas-area hospitals, said Monday that it was still treating six of those wounded, including three who were in critical condition.

Authorities have not released a motive for Garcia’s rampage, but they are investigating his suspected links to white supremacists and neo-Nazi beliefs. Garcia arrived at the mall wearing a tactical vest with a patch that read “RWDS,” which stands for Right Wing Death Squad. The phrase is popular with extremist groups including neo-Nazis and white supremacists, and authorities are trying to determine whether Garcia carried out a hate crime.

On Monday, the Allen Police Department declined to answer additional questions about the investigations, referring calls to the Texas Department of Public Safety. A spokesperson for the Department of Public Safety did not immediately respond to requests for comment.

According to his social media posts, Garcia appeared to have staked out the mall using Google to determine the busiest times.

Garcia’s social media account was first reported by the New York Times and expanded upon in a thread on Twitter by Aric Toler of the open-source investigation group Bellingcat. Toler noted that Garcia used the forum for diary-style entries and might have picked that platform “because it has virtually zero content moderation.”

The last post on Garcia’s account, dated Saturday, resembled a suicide note and included more than 500 words of violent, hateful fantasies, self-aggrandizement and pop-culture references. Older entries expressed admiration for other mass killers and described a dark worldview that included apocalyptic “accelerationist” ideology, which is associated with calls for a violent collapse of society.

Other posts on the account showed off tattoos, including a swastika and other Nazi symbols.

Although Army officials declined to specify why Garcia had been discharged, administrative separations like the one he received are meant to quickly force out recruits who can’t perform military duties as a result of various physical or behavioral conditions. They are not typically punishments and would not show up on background checks. Recruits who leave the service before they finish training don’t receive military or veterans benefits.

Authorities released the names of the adults killed but only the ages of the children who died. Some of their identities have been confirmed by family members, friends and others.

They include three members of the Cho family of Dallas: Kyu Song Cho, Cindy Cho and their 3-year-old son. A GoFundMe page said their 3-year-old was named James, while their 6-year-old son, William, was injured but was out of intensive care.

Elementary students Daniela and Sofia Mendoza were at the mall with their mom, Wylie Independent School District officials said. The girls were fatally shot; their mother, Ilda, remained in critical condition Monday.

Daniela, a fourth-grader, and Sofia, a second-grader, were “rays of sunshine,” Cox Elementary School principal Krista Wilson said in a message to parents. She called them “the kindest, most thoughtful students.”

Aishwarya Thatikonda, the engineer, who lived in McKinney, Texas, was days from her 27th birthday, her boss said. She had come to the United States from India about five years ago in pursuit of opportunities in engineering, said Ashok Kolla, a volunteer for the Indian American nonprofit Telugu Association of North America who was representing the family.

Thousands of miles away in India, her parents grew concerned when they couldn’t reach her Saturday. Kolla drove from hospital to hospital over the weekend, then to the shooting scene, then finally to the medical examiner’s office, where, after seven hours of waiting, he learned that Thatikonda was among the dead.

“All of us had hoped she was somewhere in the hospital,” Kolla said. On Monday, he was sorting through the logistics of having her remains sent home to India, trying to help her devastated parents and brother. He said the killing had sent shockwaves through the Indian community, which has had little experience with the mass shootings that haunt America.

“This girl had a long way to go, being a brilliant and well-educated kid,” Kolla said. “She had a long way to go.”

Christian LaCour, the security guard, “was tragically killed while protecting the customers and employees of the Allen Premium Outlets,” his employer, Allied Universal, said in a statement. A relative described the 20-year-old as “more amazing than anyone would ever truly know,” declining to comment further. Also killed was Elio Cumana-Rivas of Dallas, who was 32, according to the Texas Department of Public Safety.

The Allen shooting occurred a little more than a week after a gunman, armed with an AR-15-style weapon, shot and killed five of his neighbors in Cleveland, Texas. The family had asked the man, who was arrested after an extensive manhunt, to stop firing his weapon so they could sleep.

The back-to-back mass killings - taking place about a year after 19 students and two teachers were shot to death in a school in Uvalde, Texas - have increased the pressure on Texas Gov. Greg Abbott (R) and GOP lawmakers to address gun violence. But with Texas’s biannual legislative session scheduled to conclude in late May, supporters of tougher rules face a steep hurdle to persuade the Republican-controlled legislature to take action.

The committee vote Monday occurred after relatives of the Uvalde victims packed into the state House and urged lawmakers to raise the minimum age to buy certain types of firearms to 21, up from 18.

After the vote to send the measure to the House floor, some relatives cheered while others sobbed.

State Sen. Roland Gutierrez, a Democrat who represents the Uvalde area, celebrated with the Uvalde family members at lunch after the bill made it out of committee. Gutierrez said the committee vote, which included support from two Republicans, was the most significant progress on gun legislation that he’s seen in his 16 years in Austin.

But he said he and other Democratic lawmakers are tempering their optimism, knowing that the legislation still faces an uphill slog on the House floor and in the Senate.

“Hope springs eternal,” Gutierrez said. “As I told the families, there never has been a bill in my time that has been a pro-gun-safety bill that has even had a hearing in committee. This happened because of these families’ efforts.”

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Craig reported from Fort Lauderdale, Fla., and Allam, Horton and Shammas reported from Washington. The Washington Post’s Molly Hennessy-Fiske in Houston, and Razzan Nakhlawi, Samuel Oakford, Marisa Iati, Anumita Kaur and Nick Parker in Washington contributed to this report.