Armed law enforcement officers were present on Tuesday as a shooter entered an elementary school in Uvalde, Texas, and slaughtered 21 people, including 19 young children. They just didn’t do anything.

The Associated Press reported on Wednesday that onlookers urged police to go into the school and stop the massacre, to no avail. “Go in there! Go in there!” women shouted, according to one witness. Javier Cazares, whose daughter Jacklyn was killed, said police were congregated outside the building when he arrived, prompting him to suggest other bystanders rush to try to stop the carnage themselves. “Let’s just rush in because the cops aren’t doing anything like they are supposed to,” he said. “More could have been done.”

“There were more of them,” Cazares added. “There was just one of him.”

“They were just angry, especially the dads,” Derek Sotelo, who headed to the school after hearing gunfire from his tire shop nearby, told The New York Times. “We were wondering, ‘What the heck is going on? Are they going in?’ The dads were saying, ‘Give me the vest, I’ll go in there!’”

The revelation comes as conservatives who oppose common-sense gun control measures have advocated for stocking schools with armed guards, and in many cases armed teachers, to prevent mass shootings. The massacre in Uvalde on Tuesday is proof positive that doing so doesn’t guarantee anything, and that if someone who is heavily armed wants to wreak havoc, they’re going to be able to do so.

Officials say the shooter, Salvador Ramos, “encountered” an armed school district police officer outside the school, although the Times later reported that the officer was not stationed at the school and instead came from nearby after calls came into 911. Ramos was still able to make his way inside the school, however, after which he barricaded himself in a classroom. He then shot two Uvalde police officers arriving to the scene, injuring them. He continued to shoot through the wall at law enforcement as he slaughtered children in the classroom, according to the Times. Department of Public Safety Director Steve McCraw said 40 minutes to an hour passed from when Ramos encountered the officer outside the school to when he was killed by a tactical team.

Ramos had turned 18 days earlier and bought two AR-15-style rifles shortly after his birthday. The guns were bought legally. Governor Greg Abbott signed a law last summer allowing guns to be carried without a permit. Abbott said on Wednesday that instead of gun reform the government needs to “target that mental health challenge and do something about it.” Abbott has also noted that Ramos had no known history with mental health issues.

Conservatives pushing for more guns in schools is part of a broader call to “harden” them against attacks. Fox News has brought on people to suggest everything from installing “man traps” triggered by “trip wires,” to hanging up ballistic blankets, to erecting a “ring of steel” around schools. Sen. Ted Cruz (R-Texas) was in Uvalde on Wednesday to argue that schools should have bulletproof glass, bulletproof doors, and only one entrance.

Schools having only one door — which sounds like quite a fire hazard! — and most of the other conservative solutions to the mass shooting epidemic are as ludicrous as they are impractical, especially considering the Uvalde school district already had a multi-faceted safety plan in place. NBC News reported on Wednesday that the district had doubled its safety plan in recent years in response to the 2018 shooting at Santa Fe High School in Houston. The district had its own police force. It had threat assessment teams working at every school. There was a system to report threats. There were fences around schools. Teachers were required to lock classroom doors.

It didn’t matter at Robb Elementary on Tuesday. Nor did it matter that an armed security officer was outside the school, or that police were quick to respond. All that mattered was that Salvador Ramos was able to buy some guns after he turned 18, and that he wanted to use them to kill a bunch of schoolchildren.