The gunman who massacred 19 children and two teachers at a Texas elementary school was inside for more than an hour before he was killed in a shootout, US law enforcement authorities said, amid mounting public anger and scrutiny over their response to the rampage.
A media briefing called by Texas public safety officials to clarify the timeline of the attack provided bits of previously unknown information.
By the time it ended, though, it had added to the troubling questions surrounding the attack, including about the time it took police to reach the scene and confront the gunman, and the apparent failure to lock a school door he entered.
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Instead, Ramos entered the building "unobstructed" through an apparently unlocked door, said Victor Escalon, regional director for the Texas Department of Public Safety.
Local police officers entered the building four minutes later but were driven back after exchanging fire with the gunman, he said.
The crisis did not end until a group of Border Patrol agents went in nearly an hour later.
Ramos, who had staked out a spot in the fourth grade classroom he targeted, was killed during the shootout, Escalon said.
Many other details of the case and the police response remained murky.
The motive for the massacre — the nation's deadliest school shooting since Newtown, Connecticut, a decade ago — remained under investigation, with authorities saying Ramos had no known criminal or mental health history.
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During the siege, frustrated onlookers urged police officers to charge into the school, according to witnesses.
"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.
Carranza said the officers should have entered the school sooner: "There were more of them. There was just one of him."
Texas Department of Public Safety Director Steve McCraw defended the agency on Wednesday, saying: "The bottom line is law enforcement was there. They did engage immediately. They did contain (Ramos) in the classroom."
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Border Patrol Chief Raul Ortiz did not give a timeline but said repeatedly that the tactical officers from his agency who arrived at the school did not hesitate.
He said they moved rapidly to enter the building, lining up in a "stack" behind an agent holding up a shield.
"What we wanted to make sure is to act quickly, act swiftly, and that's exactly what those agents did," Ortiz told Fox News.
But a law enforcement official said that once in the building, the Border Patrol agents had trouble breaching the classroom door and had to get a staff member to open the room with a key.
The official spoke on condition of anonymity because he was not authorised to talk publicly about the investigation.
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Department of Public Safety spokesman Lieutenant Christopher Olivarez told CNN that investigators were trying to establish whether the classroom was, in fact, locked or barricaded in some way.
Javier Cazares, whose fourth grade daughter, Jacklyn Cazares, was killed in the attack, said he raced to the school as the massacre unfolded.
When he arrived, he saw two officers outside the school and about five others escorting students out of the building.
But 15 or 20 minutes passed before the arrival of officers with shields, equipped to confront the gunman, he said.
As more parents flocked to the school, he and others pressed police to act, Cazares said. He heard about four gunshots before he and the others were ordered back to a parking lot.
"A lot of us were arguing with the police, 'You all need to go in there. You all need to do your jobs.' Their response was, 'We can't do our jobs because you guys are interfering,'" Cazares said.
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Ramos crashed his truck into a ditch outside the school, grabbed his AR-15-style semi-automatic rifle and shot at two people outside a funeral home, who ran away uninjured, according to authorities and witnesses.
As for the armed school officer, he was driving nearby but was not on campus when Ramos crashed his truck, according to a law enforcement official who was not authorised to discuss the case and spoke of condition of anonymity.
Investigators have concluded that school officer was not positioned between the school and Ramos, leaving him unable to confront the shooter before he entered the building, the law enforcement official said.
