Beto O’Rourke interrupts a news conference by his opponent, Gov. Greg Abbott, accusing him of ‘doing nothing.’

Former Representative Beto O’Rourke interrupted a news conference hosted by Gov. Greg Abbott of Texas on Wednesday to accuse Republicans of “doing nothing” to address gun violence in the aftermath of a shooting at an elementary school in Uvalde, Texas.

Mr. O’Rourke, an unsuccessful Democratic presidential candidate who is now running for governor, stood in front of a stage at the civic center in Uvalde, 20 minutes into the news conference held by Mr. Abbott and officials, and shouted that the killings were a “totally predictable” result of lax state and federal gun laws.

When Mr. Abbott’s allies saw Mr. O’Rourke step forward, they began shouting at him, with the mayor of Uvalde, Don McLaughlin, hurling an obscenity, another ordering the El Paso native to “Shut up!” and the state’s lieutenant governor, Dan Patrick, demanding that he sit down.

Mr. O’Rourke, dressed in his signature powder blue dress shirt, did not comply. Moments later, uniformed security guards grabbed Mr. O’Rourke and pulled him away.

On his way out, he could be heard telling the audience, some of whom were jeering him while others yelled to let him speak, “Somebody needs to stand up for the children of this state, or they will continue to be killed.”

Mr. O’Rourke’s move drew both scorn and praise.

To Republicans, he was exploiting a tragedy in front of the cameras as he tries to draw attention to his longshot bid for governor. To Democrats, it showed a desperation in their efforts to push for gun control, as a former congressman resorted to a more confrontational protest tactic. Republicans in Washington and red state capitals have successfully blocked even modest gun control reforms in the wake of mass killings involving semiautomatic weapons, most of them legally purchased.

“The time to stop this was after Santa Fe,” Mr. O’Rourke said at the civic center, referring to the Texas high school shooting near Houston in 2018. “The time to stop this was after El Paso,” he added, referring to the Texas mass shooting at a Walmart in 2019.

“The time to stop the next shooting is right now, and you are doing nothing. You are offering us nothing. You said this was not predictable — this is totally predictable when you choose not to do anything,” he said.

After Mr. O’Rourke left the room, Mr. Abbott criticized him for the outburst.

“There are family members who are crying as we speak,” he said. “Think about the people who are hurt and help those who are hurt.”

Mr. Patrick added: “This is not a partisan issue. This is not a political issue.”