Beto O'Rourke, a candidate running for governor of Texas, interrupted a press conference held by current Gov. Greg Abbott Wednesday, shouting at Abbott before being escorted from the building.

O'Rourke protested the current governor's stance on gun control.

"You are doing nothing!” he shouted.

Six people injured in the Texas elementary school shooting remain hospitalized on Wednesday.

Three children and one adult are at the University Hospital in San Antonio, two of whom are in serious condition.

Two other adults are hospitalized at Brooke Army Medical Center, both in serious condition.

All patients treated at Uvalde Medical Center have been discharged. The hospital said it treated 15 individuals, 11 of whom were children. Three of those 11 children were transferred to other hospitals in San Antonio and eight were discharged home.

The four remaining patients were adults, one was transferred to another hospital and three were discharged home.

-ABC News' Jennifer Watts

Jacinto Cazares, the father of Jacklyn Jaylen Cazares, a 10-year-old killed in the Texas elementary school shooting, told ABC News he blames the school and police for the massacre, not the murder weapons.

"I want to say we hold the school responsible for not having locked doors and no protocol, no training. Also the Police for not having a better and faster tactical response time. There was at least 40 lawmen armed to the teeth, but didn't do a darn thing till it was far too late," Cazares told ABC News in a statement.

He added, "The situation could've been over quick if they had better tactical training and we as a community witnessed it first hand. I'm a gun owner and I do not blame the weapons used in this tragedy. I'm angry how easy it is to get one and young you can be to purchase one."

-ABC News' Miles Cohen

Secretary of Homeland Security Alejandro Mayorkas said the department is "horrified by this callous act of violence," in a statement Wednesday.

Mayorkas said one Border Patrol agent was injured in the crossfire.

"We are grateful for the courageous members of our Border Patrol, many of whom are part of the Uvalde and surrounding communities, who immediately responded to the scene along with local and state law enforcement," Mayorkas said.

He added, "Without hesitation, they put themselves between the shooter and students to end the bloodshed and administer medical aid. Without question, their heroism yesterday saved lives."

The department will continue to coordinate with local, state and federal partners, Mayorkas said.

"As we pray for the families and loved ones and recognize the bravery of frontline law enforcement personnel, we must redouble our collective efforts to make our communities safer," Mayorkas said.

The Justice Department will conduct a critical incident review to examine the law enforcement response to last week’s school shooting in Uvalde, Texas, a spokesperson announced on Sunday.

The review is being conducted at the request of Uvalde Mayor Don McLaughlin and the DOJ will publish a report on its findings at the conclusion.

"The goal of the review is to provide an independent account of law enforcement actions and responses that day, and to identify lessons learned and best practices to help first responders prepare for and respond to active shooter events. The review will be conducted with the Department’s Office of Community Oriented Policing," the DOJ said in a statement.

“As with prior Justice Department after-action reviews of mass shootings and other critical incidents, this assessment will be fair, transparent, and independent. The Justice Department will publish a report with its findings at the conclusion of its review.”