Two sisters, in 2nd grade and 4th grade, among dead in mall shooting

(ALLEN, Texas) — Eight victims were killed when a gunman opened fire at shoppers at the Allen Premium Outlets in Allen, Texas, on Saturday.

Here is what we know about the lives lost:

Christian LaCour

Christian LaCour, 20, died during the Allen, Texas shooting, his sister, Brianna Smith, confirmed to ABC News.

LaCour was an on-duty security guard at the outlet mall where the shooting occurred, his sister said.

“He was a really sweet kid,” Brianna Smith told ABC News over the phone. “I’m sad that he’s gone.”

Christian’s mother, Tracye LaCour, asked for privacy, telling ABC News they are praying for the families of the other victims.

Daniela Mendoza and Sofia Mendoza

Daniela Mendoza, a fourth grader, and sister Sofia Mendoza, a second grader, were both killed in the shooting, Wylie Independent School District Superintendent David Vinson said in a statement.

“Daniela and Sofia were the kindest, most thoughtful students with smiles that could light up any room,” their principal, Krista Wilson, said in a statement. “Our hearts are broken and words cannot express how deeply they will be missed.”

Daniela and Sofia’s mom, Ilda, is in critical condition from the shooting, Vinson said.

“Words cannot express the sadness we feel as we grieve the loss of our students. Our thoughts and prayers are with the Mendoza family, the families of the victims, and all those affected by this senseless tragedy,” Vinson said.

“We are not announcing the news to students, as we want our parents to be able to have those conversations,” Vinson added. “Every school’s counseling team is equipped to support those who may be struggling, so please do not hesitate to reach out.”

Aishwarya Thatikonda

Aishwarya Thatikonda, an engineer who lived in McKinney, Texas, was also among the victims, Dallas ABC affiliate WFAA reported.

She was at the mall with a friend, who was injured and hospitalized, a family representative told WFAA

Thatikonda’s family plans to have her body sent to India, where her relatives are located, WFAA reported.

This is a developing story. Please check back for updates.

ABC News’ Miles Cohen and Alyssa Pone contributed to this report.