As many of those wounded in a horrific mass shooting at a Texas outlet mall over the weekend are still being treated in hospitals, investigators have yet to pin down a motive for the attack.

Eight people were killed and at least seven others injured on Saturday when a 33-year-old gunman opened fire at the Allen Premium Outlets in a northern suburb of Dallas. Witnesses have described a gruesome scene with some victims riddled with atrocious gunshot wounds as bystanders rushed to perform first aid.

"Ambulances came and the medics were shocked," said Steven Spainhouer, who tended to victims in the mall parking lot.

"We were going to try and triage on the site but they said, 'No, These horrific injuries ... we can't triage. Just load them in the ambulance and go," Spainhouer said.

One of those injured was in critical condition and another in serious condition as of Tuesday, according to Medical City Healthcare, which is treating six of the wounded.

Two others were in fair condition and the remaining two, including one at Medical City Children's Hospital, were in good condition, said the healthcare network, which has not named any of its patients.

Many of those killed were from the same two families, including a married couple and their 3-year-old son and two elementary school-aged sisters -- Daniela and Sofia Mendoza.

Daniela and Sofia's mother, Ilda Mendoza, was hospitalized in critical condition on Monday, according to a letter sent to parents by the girls' school district. Her current condition is unclear.

Irvin Walker II had to undergo surgery after the gunman fired directly into his car, striking him twice in his chest and once in the shoulder, according to a verified GoFundMe set up on his behalf. Walker's surgery was successful and he is stable, the page says.

The shooter, identified as Mauricio Garcia, was carrying three weapons, including an incredibly destructive AR-15-style rifle, and had five more in his car, Texas Department of Public Safety Regional Director Hank Sibley said Tuesday.

All of the firearms Garcia brought were legally obtained, Sibley said.

But as witnesses and authorities have painted a vividly grim picture of how the attack unfolded, investigators have still not arrived at a motive in the nation's second-deadliest massacre this year.

Though investigators have found Garcia had "neo-Nazi ideation," Sibley said the shooter did not appear to be targeting people based on their ethnicity.

"To me, it looks like he targeted a location rather than a specific group of people," Sibley said.

As the probe continues, the FBI is warning that scammers may be trying to take advantage of the tragedy.

"We are aware of multiple fake online fundraisers that are currently underway for the victims," said Chad Yarbrough, special agent-in-charge for FBI Dallas.

Shooter's background reveals extremist ideation

As investigators continue to analyze Garcia's electronics and social media, several details of the shooter's background have already emerged, including online posts in which he appears to have espoused support for Nazism and obsessed over guns and prior mass shootings.

Sibley also said Tuesday that Garcia had tattoos and patches expressing neo-Nazi ideation.

A photo from the shooting scene obtained by CNN show's Garcia lying on the ground after being shot. He is wearing a patch that reads "RWDS," which authorities believe may stand for "Right Wing Death Squad," a senior law enforcement source familiar with the investigation told CNN.

The insignia also appears to be shown in a photo posted by an account user on the Russian social media website Odnoklassniki that a law enforcement source said investigators believe belongs to Garcia.

The user also posted writings supporting Nazi ideology and, in the weeks before the shooting, posted a photo of the mall.

A few weeks before the shooting, the user also posted a screenshot from Google Maps showing what times of day the outlet mall was busiest.

Garcia, who had previously worked as a security guard, had no documented criminal history, Sibley said.

Slain security guard was working to evacuate shoppers

Authorities say Christian LaCour, a 20-year-old mall security guard, was killed while trying to escort people to safety.

"We also must acknowledge the bravery of Allied (Universal) security guard Christian LaCour, who evacuated one individual to safety and was shot while courageously remaining to help others," Allen Police Chief Brian Harvey said.

LaCour was "the kind of person who would just walk into the store and everyone in the room would light up because he was there," said Max Weiss, a mall store employee.

Another victim, Elio Cumana-Rivas, worked hard as a delivery driver to support his parents who live in Venezuela, his brother Gregory Smith Cumana told CNN

"We were all very close," said Cumana. "He helped his mother buy her medicine, and he would also contact our dad and make sure he had everything he needed."

The attack also devastated a Korean American family -- turning their family of four into a family of one after a 6-year-old's parents, Cho Kyu Song, 37, and Kang Shin Young, 35, and 3-year-old brother were all killed.

James, the young brother, loved wearing elephant bibs and shirts, his day care teacher Trinity Whitley told CNN affiliate WFAA.

"He was a super sweet kid and every day we're going to miss him. And there won't be a day we're not thinking about him," she said.