A memorial outside the Allen Premium Outlets continues to grow.

Dallas native Roberto Marquez has made it his life’s work to create memorials at the scene of tragedies. He told ABC News that this memorial in Allen is his 11th.

Marquez said Home Depot donated the lumber he used to build the crosses.

Volunteers from Lutheran Church Charities have also arrived at the scene with therapy dogs. The group has over 140 dogs in at least 25 states.

The same dogs in Allen on Monday were on the scene in Uvalde last year when 19 students and two teachers were killed in a mass shooting at Robb Elementary school.

A vigil for the Allen victims is set for Wednesday at 7 p.m., according to community leaders.

-ABC News' Ike Ejiochi and Abigal Shalawylo

After a gunman opened fire at the Allen Premium Outlets, Joshua W. Barnwell, an eyewitness with military experience, rushed to help the wounded.

A woman who was conscious asked him to help her daughter, he said.

"This woman had massive trauma, five to six gunshot wounds," Barnwell told "Good Morning America" on Monday.

He went to the daughter to start chest compressions, he said.

"When I saw the massive amount of blood come out from her when I gave her chest compressions to her back," Barnwell said. "I knew she was gone."

Vice President Kamala Harris released a statement Sunday about the shooting, also urging Congress to act.

"Doug and I mourn for the eight adults and children who lost their lives, pray for those wounded, and send our gratitude to the first responders who ran toward danger," she said in a statement.

"All Americans deserve to be safe from gun violence. But they are not," Harris continued. "Not because we do not know the solutions. Not because the American people are divided on this issue -- even a majority of gun owners support sensible reforms."

Harris urged Congress to send a bill to President Joe Biden that would ban assault weapons and high-capacity magazines, and would introduce universal background checks.

"We need action," Harris added.

-ABC News' Molly Nagle

The FBI has provided details to the public on how they can retrieve their vehicles from the outlet mall.

Those with vehicles that were left at the mall can meet at the Allen Senior Recreation Center beginning at 5:45 p.m. local time Sunday, where they will be sent to the outlet mall, the FBI said Sunday in a press release.

The senior center will be managing the retrievals until 9:30 p.m. local time, the FBI said.

"Please drop off only one individual for vehicle retrieval," the FBI said. "Be sure to have your car keys with you."

Officials have urged the public not to go directly to Allen Premium Outlets.