Gabriella Borter and Brad Brooks

UVALDE (Texas) – Police response to the Texas school shooting massacre on Tuesday was being scrutinized more closely than usual Friday. This comes a day after officials acknowledged that the attacker entered the classroom and shot dead 19 students and 2 teachers, while also barricading him inside.

The National Rifle Association (the country’s most prominent gun rights advocacy and lobby group) opened its annual Houston meeting Friday even as the attack – which has been the worst U.S. school shooting in almost a decade-intensified the ongoing national debate about gun laws. Prominent Republicans including the former president Donald Trump and U.S. Ted Cruz, a Texas Senator, was scheduled to speak at the convention.

Greg Abbott, Republican Governor of Texas, was also scheduled to address the meeting. Instead, he will record remarks and travel to Uvalde (the scene where the shooting occurred) to give a news conference along with other officials.

Joe Biden, a Democrat, who has urged Congress for new restrictions on guns, will visit Uvalde Sunday.

Officials provided more details Thursday about the brutal rampage perpetrated at Robb Elementary school in Uvalde by Salvador Ramos, an 18-year old from the community of 16,000 residents located about 80-miles (130 km) west San Antonio.

This new timeline was very different to some of the previous official accounts. There are new questions as to whether or not police had an earlier chance to intervene.

Video footage of parents begging officers for help at the school was released earlier Thursday. Some fathers had to be restrained by police.

Victor Escalon, spokesperson for Texas Department of Public Safety said that preliminary reports that Ramos crashed his truck in front of the school were incorrect.

Ramos instead scaled a fence to enter through an unlocked gate at 11:40 AM (1640 GMT), twelve minutes after the accident. Miguel Cerrillo said the door may have been open because parents were there to present awards to third-graders at the school.

Escalon reported that the two officers who responded entered the school shortly after Ramos opened fire on them.

Escalon reported that after the shooter had barricaded himself in the fourth-grade classroom, most of his victims were 9- or 10-year-olds. After an hour, a U.S. Border Patrol tactical group entered the room to fatally shoot him.

The time between agents entering appeared to have been inconsistent with the law enforcement agency’s approach to dealing with “active shooters” in schools to end bloodshed.

Escalon was asked if police should have entered earlier and replied, “That is a difficult question,” and that the authorities would provide more information as they investigate.

On Friday, law enforcement officers will again brief media.

An announcement that the husband of one the teachers who were killed in the tragedy intensified the human toll. He died on Thursday as he prepared for the funeral of his wife.

The motive is still being investigated by investigators. Ramos, who was high school dropout and had no criminal records or history of mental illnesses, is still being sought by investigators. According to Governor Abbott, Ramos had posted an anonymous message online announcing that he would “shoot-up an elementary school” minutes before the attack.

Salvador Ramos (42) was the father of the gunman. In an interview, published by The Daily Beast, he expressed his regret at his son’s actions. His grandmother was the one who had raised him.

“I just want the people to know I’m sorry, man, (for) what my son did,” the elder Ramos told the site. “He should’ve just killed me, you know, instead of doing something like that to someone.”