“There was at least 40 lawmen armed to the teeth but didn’t do a darn thing [until] it was far too late,” Javier Cazares, the father of 10-year-old victim

The teenage madman who slaughtered 19 kids and two teachers in a Texas school spent more than 40 minutes inside as witnesses desperately urged police to charge into the building, it was ­revealed Wednesday.

Salvador Ramos barricaded himself inside the classroom before opening fire on students and teachers inside. Border Patrol agents finally breached the door about 40 minutes to an hour later when a staff member gave them a key.

Now a father of one of the dead children is blaming officers at the scene for not acting sooner to stop the gunman.

Cazares raced to Robb Elementary School when he heard about the shooting and arrived while police were still gathered outside.

While he watched anxiously at the officers standing outside his daughter’s school, he suggested storming into the school building himself alongside other civilian bystanders.

“Let’s just rush in because the cops aren’t doing anything like they are supposed to,” he said he told other onlookers. “More could have been done.”

“There was at least 40 lawmen armed to the teeth but didn’t do a darn thing [until] it was far too late,” Javier Cazares, the father of 10-year-old victim Jackie Cazares, told ABC News.

A witness who lived across the street from the elementary school, said onlookers begged officers outside the school to do something as bullets rang inside the building.

“Go in there! Go in there!” nearby women shouted at the officers who did not go inside, 24-year-old Juan Carranza said.

Local police, state police and 80 Border Patrol officers swarmed to the scene. Four of the 80 Border Patrol officers entered the school building and killed Ramos, according to a Customs and Border Protection official.

Carranza felt the officers should have barged into the school quicker.

“There were more of them, there was just one of him,” he said.

U.S. Border Patrol Chief Raul Ortiz said in a Wednesday interview with CNN that as soon as the Border Patrol officers arrived, “they didn’t hesitate.”

“They didn’t hesitate. They came up with a plan,” Ortiz told the outlet. “They entered that classroom and they took care of the situation as quickly as they possibly could.”

Carranza said he first watched Ramos crash his truck in a ditch outside the school, grab a AR-15-style semi-automatic rifle and shoot at, and miss, two people outside a nearby funeral home.

The mass shooter then fired at a school district security officer, ran inside the elementary school and shot at two arriving Uvalde police officers outside the building, according to a Texas Department of Public Safety spokesperson, who added that all three officers were injured.

It’s unclear whether the school security officer shot back at Ramos.

Ramos barged into one classroom, locked the door behind him and allegedly began massacring fourth-grade students and their teachers, according to the public safety department.

Department of Public Safety Director Steve McCraw said it was “within 40 minutes or so” from when the 18-year-old opened fire on the school security officer to when the Border Patrol team shot him.

The specialized, SWAT-like team known as the Border Patrol Tactical Unit struggled to breach the classroom door and had to get a staff member to open it with a key, a law enforcement official who requested anonymity told the Associated Press.

Cazares said the officers needed better tactical training and and were unprepared.

“The situation could’ve been over quick if they had better tactical training, and we as a community witnessed it firsthand,” he told ABC News.

He also said young people like the 18-year-old who killed his daughter shouldn’t be able to buy guns.

“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 how young you can be to purchase one,” he said.