Hours after the 18-year-old gunman killed at least 20 children and 2 adults at Uvalde elementary school in Texas, US President Joe Biden addressed the nation on Tuesday night, focusing on tighter gun control law.

Read more: US statistics 2022: 140+ mass shootings, 5 mass murders so far

What he failed to mention was the police's response time in regard to the incident. 

The gunman, Salvador Ramos, first arrived at the site of the school at 11:28 am, and at 12:58 pm, law enforcement received the alert that he had been killed. What transpired in those 90 minutes has stoked public outrage and criticism of police enforcement's response to Tuesday's assault.

Javier Cazares's fourth-grade daughter was killed on Tuesday. Cazares rushed to the school as the events unfolded and said he did not see police rush into the building as they claimed.

“They say they rushed in... We didn’t see that,” Cazares said.

Authorities mostly disregarded queries about why cops were unable to stop the gunman sooner on Thursday, with Victor Escalon, regional director for the Texas Department of Public Safety, assuring reporters he had “taken all those questions into consideration” and would provide information later.

A media conference revealed previously undisclosed details. However, by the time it concluded, it had added to the worrisome concerns surrounding the incident, such as the time it took police to get on the scene and face the gunman, as well as the apparent failure to lock a school door he entered.

Investigators revealed, after two days of delivering frequently contradictory information, that a school district police officer was not inside the school when Ramos arrived and that, contrary to prior reports, the officer had not approached Ramos outside the facility.

Instead, they drew a chronology that was remarkable for inexplicable delays by law enforcement.

Ramos opened fire on two persons coming out of a local funeral home after his truck crashed, according to Escalon. At around 11:40 am, he entered the school "unobstructed" through an apparently unlocked entrance.

However, the first policeman arrived on the site 12 minutes after the collision and did not enter the school to follow the gunman until four minutes later. Ramos' shooting drove them back, and they took refuge, according to Escalon.

The incident ended about an hour later, around 12:45 pm, when a group of Border Patrol tactical officers entered the school, according to Texas Department of Public Safety Spokeswoman Travis Considine. They exchanged gunfire with the shooter, who was holed up in the fourth-grade classroom. He died just before 1 pm.

During that moment, the cops summoned backup, negotiators, and tactical teams, while also evacuating children and instructors, according to Escalon.

The length of the schedule, according to Ken Trump, owner of the consulting firm National School Safety and Security Services, raises concerns.

According to Trump, “Based on best practices, it’s very difficult to understand why there were any types of delays, particularly when you get into reports of 40 minutes and up of going in to neutralize that shooter."

According to witnesses, furious bystanders pushed police officers to storm into the school during the siege.

Acting not so quickly

“Go in there! Go in there!” women shouted at the officers soon after the attack began, said Juan Carranza, 24, who watched the scene from outside a house across the street.

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

Border Patrol Chief Raul Ortiz claimed that the tactical personnel from his agency who arrived at the school did not hesitate. “What we wanted to make sure is to act quickly, act swiftly, and that’s exactly what those agents did,” Ortiz said to Fox.

However, according to a law enforcement official, once inside the facility, the agents had difficulty breaking the classroom door and had to rely on a staff member to access the room with a key. 

Lt. Christopher Olivarez, a spokesperson for the Department of Public Safety, told CNN that detectives were attempting to determine whether the classroom was really locked or barricaded in some manner.

When Cazares arrived, he noticed two cops outside the school and around five more ushering pupils out. However, he claimed that 15 or 20 minutes elapsed before cops with shields arrived to face the gunman.

As additional parents arrived at the school, he and others urged authorities to intervene, according to Cazares. He heard four gunshots before being told to return to a parking lot with the others.

Cazares explained that many parents argued with police and told them to do their jobs and go inside. He said that the police responded by saying, "We can’t do our jobs because you guys are interfering."

According to a law enforcement official who spoke on condition of anonymity, the armed school officer was driving close but was not on campus when Ramos crashed his truck.

The investigation found that he was unable therefore to confront the shooter before he made his way into the building.

Michael Dorn, executive director of Safe Havens International, which works to make schools safer, cautioned that it might be difficult to acquire a thorough picture of the facts immediately following a massacre.

According to Dorn, “The information we have a couple of weeks after an event is usually quite different than what we get in the first day or two. And even that is usually quite inaccurate."

He explained that for catastrophic events, "you're usually eight to 12 months out before you really have a decent picture."