In the wake of a spate of mass shootings, including in Allen, Texas, Senate Majority Leader Chuck Schumer has called a special caucus meeting for Senate Democrats to discuss gun violence and the path forward on gun safety legislation, according to a Schumer spokesperson.

The meeting is set for Thursday, May 11 at 12:45 p.m. ET.

-ABC News' Trish Turner

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

As authorities work to determine a motive for the outlet mall shooting in Allen, Texas, one avenue investigators are exploring is whether this was an act of domestic terrorism, multiple law enforcement sources told ABC News.

The shooter wore patches or stickers on his clothing that raised suspicion he may have gravitated toward right-wing extremism, the sources said, though they added no motive has yet been established.

Federal agents were seen at a home in the Dallas area believed to be associated with the shooter, ABC Dallas affiliate station WFAA reported.

Federal investigators are already going through the suspect’s electronic devices and social media as they work to understand what led to the killing rampage, the sources said.

In addition to a rifle used in the shooting, sources said investigators recovered additional firearms in a vehicle associated with the shooter.

The Texas Rangers are the lead agency on the case with assistance from the FBI, ATF and Allen police.