The U.S. Attorney is treating the El Paso mass shooting as a domestic terrorism case, the Associated Press reported.

John Bash, the U.S. Attorney, said on Twitter, “... we’re treating El Paso as a domestic terrorism case. And we’re going to do what we do to terrorists in this country—deliver swift and certain justice.”

That “swift and certain justice” could include the death penalty.

The shooting on Saturday killed 20 people and hurt 26 others were injured in an attack at an El Paso shopping center.

One suspect is in custody, according to police. A police official told the Associated Press the suspect in custody is Patrick Crusius, 21, from the Dallas area.

An AP source said the Justice Department is considering hate crime charges against the suspect that would carry the death penalty.

Law enforcement would not confirm the suspect’s name, but jail sources confirm he has been booked on capital murder charges. The El Paso Police Department says they have a manifesto from the suspect that has led them down that avenue of investigation. Police say there are reports that a rifle was used in the shooting.

Police said in a news conference Saturday afternoon that they received 911 calls about a shooting at a Walmart near Cielo Vista Mall around 10:30 a.m.

Police spokesman Sgt. Robert Gomez said they believe most of the victims were shot at the Walmart and not the mall. Gomez said up to 3,000 shoppers were in the store at the time along with around 100 employees. The store was full of back-to-school shoppers.

A 25-year-old woman, Jordan Anchondo, was among those shot to death at Walmart while shopping for back-to-school supplies.

The sister of Anchondo, Leta Jamrowski, 19, of El Paso, said she likely was trying to shield her 2-month-old son and fell on him as she was shot, the AP reported. The infant suffered broken bones and is being treated at an El Paso hospital.

Jamrowski was waiting for word on the status of her brother-in-law.

The FBI is asking anyone who took video or photos of the shooting to submit them online.

Mexican President Andrés Manuel López Obrador said on Twitter three of the deceased were Mexican citizens. Additionally, Mexico’s Secretary of Foreign Affairs, Marcelo Ebrard, said six Mexicans were injured.

Steven Flaherty, Trauma medical director, at Del Sol Medical Center, said in a news conference Sunday morning they received 11 patients ranging in age from 35 to 82. Eight are in stable condition and three are in critical condition.

“Many of them were operated on,” he said. “We anticipate a number of the patients will need to return to the operating room.”

Flaherty commended surgeons and other healthcare providers for coming in on their days off to help with the trauma situation.

“Large volumes of blood and blood products were used,” and he paid tribute to those who took the opportunity to donate blood during this emergency situation.

Another 13 were taken to University Medical Center of El Paso. A spokesperson said during an interview with CNN one person taken there died of his or her injuries. The spokesperson also said two children, ages 2 and 9, were stabilized there before being taken to neighboring El Paso Children’s Hospital.

El Paso police say there is an urgent need for blood donations. Long lines are reported outside blood donation centers in the area.

Police say they have secured both Walmart and the mall and there is no longer a threat.

Video on social media shows people running towards police with their hands up, and officers in tactical gear.

“A little kid ran in there and was telling us there’s an active shooter at the Walmart, but we didn’t pay him no attention because for one, he was just a little kid, and for two, you’re at the mall and not the Walmart,” witness Specialist Glendon Oakley told CNN. “I walked to Foot Locker and heard two gunshots and saw a lot of people running around, screaming.”

El Paso police tweeted Saturday that officers were responding to an active shooting scene and that people were advised to stay away from the Cielo Vista Mall area. The mall complex is near Interstate 10 and on El Paso’s east side.

Three businesses were on lockdown, including Hooters, Red Lobster and a Landry’s Seafood House.

Three Walmart employees took refuge in Landry’s.

“We never thought it would be so close to us this time,” Landry’s manager Oscar Collazo told CNN. “You see on the news all the time, but you don’t think it could happen here until it does.”

Walmart tweeted a statement saying they are in shock after the shooting and are working with law enforcement.

President Trump tweeted his support for the people of El Paso just after 4 p.m.

Several hundred volunteers for groups seeking tougher laws on guns marched on the White House and the Capitol late Saturday in a demonstration at least partly inspired by the shooting, according to the Associated Press.

KWCH reports a couple formerly from Salina, Kansas was hurt in the shooting.

Norma Coca said her daughter and son-in-law were at the Walmart in El Paso to raise money for their son's baseball team. Memo Garcia and Jessica Coca Garcia were near the front doors when they were shot.

Coca said her daughter Jessica was shot three times in the leg, but is in stable condition. Her son-in-law was shot twice in the leg and once in the back. He is out of surgery, but his condition is unknown.

“My grandkids were with them too. My grandson got trampled over and his face got all banged up,” Coca said. “We are just worried. We just told her our prayers are with her and we are on our way.”