Texas police have said the gunman who shot 21 people dead at a school last week entered through a door that was supposed to lock, but somehow did not.
The Texas Department of Public Safety (DPS), which is investigating the shooting response, confirmed a teacher had initially propped open the door.
But a spokesman on Tuesday said the teacher closed the door once the gunman entered the campus.
Public anger has risen as new details of the shooting emerge.
Initial reports of the gunman getting into the school via an exterior door that was accidentally left open by a teacher had suggested a breach of school policy. Employees at Robb Elementary School are required to keep doors closed and locked.
However, an attorney for the unnamed employee told the San Antonio Express-News on Tuesday that she had closed it and “thought the door would lock because that door is always supposed to be locked”.
Don Flanary said the woman had propped the door open with a rock so she could carry food from a car into a classroom, but she “kicked the rock away when she went back in” after realising a gun-wielding assailant was on campus.
Texas DPS spokesman Travis Considine said on Tuesday that video footage verified the door had been shut. He said investigators were now looking into why it had not locked.
“She came back out while on her phone, she heard someone yell, ‘He has a gun!’, she saw him [the gunman] jump the fence and that he had a gun, so she ran back inside,” Mr Considine said, adding that the employee had removed the rock as she re-entered the building.
The DPS also confirmed on Tuesday that Uvalde school district police chief Pete Arredondo had not yet responded to a Texas Rangers’ request made “a couple of days ago” for a follow-up interview.
The school and the city police force have faced intense scrutiny since last week’s attack.
At a heated news conference on Friday, DPS chief Steven McCraw confirmed 19 police officers had lingered in the hallway as the gunman barricaded himself inside a classroom.
He said the commanding officer had waited until the school janitor arrived with the keys because he did not believe it was still an “active shooter” situation.
“Of course it was not the right decision,” Mr McCraw said. “It was the wrong decision.”
The first funerals after the shooting took place on Tuesday, as Amerie Jo Garza and Maite Rodriguez, both 10, were laid to rest.
More funerals are planned for Wednesday, including a joint service for Irma Garcia, a 48-year-old teacher, and her husband, who died of a suspected heart attack two days after the shooting.
Meanwhile, President Joe Biden said he plans to meet members of Congress to look for any possible way forward on gun control.
But the prospect of any such measure passing on a polarised Capitol Hill is widely seen as being unlikely.
