Texas school shooting: Suspect's grandmother upgraded to good condition

There was blood in the hallway and children were covered in it, one of the students who survived the mass shooting at Robb Elementary School in Uvalde, Texas, told ABC News.

Samuel Salinas was a student in Irma Garcia's fourth grade class. They were scheduled to graduate Thursday, but the ceremony was canceled because Garcia, another teacher and 19 third and fourth grade students were killed in Tuesday's massacre.

Salinas said his aunt dropped him off for school on Tuesday morning.

"It was a normal day until my teacher said we're on severe lockdown," he told ABC News, "and then there was shooting in the windows."

Salinas said the gunman came into his classroom, closed the door and told them, "You're all going to die," before opening fire.

"He shot the teacher and then he shot the kids," Salinas said, recalling the cries and yells of students around him.

-ABC News' Samira Said

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Texas shooting survivor says gunman told them, ‘You’re all gonna die’

Samuel Salinas, 10, a student at Robb Elementary School, details the shooting that claimed the lives of his teacher and some of his classmates.

Sources told ABC News the accused school shooter’s mother, Adriana Reyes, at one point worked at Oasis Outback, the same store where the gunman purchased two weapons just after his 18th birthday earlier this month.

The establishment is half gun retailer, half restaurant; Reyes’ employment was with the restaurant portion, sources say.

It is unclear if she had any role in her son’s purchase of the firearms. The owner of Oasis declined to comment to ABC News and added he would only speak with law enforcement at this time. Reyes has not responded to ABC News’ request for comment.

-ABC News' Matt Gutman, Laura Romero and Victor Ordonez

The response by school officials and law enforcement is becoming a key focus in the ongoing investigation into the Uvalde school shooting, law enforcement sources told ABC News Thursday.

It is unclear whether any students and teachers heard an official call for a lockdown once the gunman entered the building, the sources said.

Additionally, investigators are looking into whether officers on site could have made other attempts to enter the school to end the gunman’s rampage faster, the sources said. Responding police were met with gunfire and called for tactical teams with proper equipment to enter the classroom and neutralize the gunman, according to the sources.

-ABC News' Matt Gutman, Josh Margolin, Aaron Katersky and Luke Barr

A student who was in the classroom next door to the one the gunman entered recounted to ABC News what she did next.

Gemma Lopez, 10, said she heard five to six gunshots and commotion outside her classroom at Robb Elementary School before a bullet whizzed by her arm and into the wall. She recalled seeing a puff of smoke, which is when she knew they were all in danger.

She said she turned off the lights and then ducked under the tables -- what she learned to do in the active shooter training she has undergone since kindergarten. There were no locks inside and they did not have a key in the classroom to lock the door from the inside, she said.

Authorities yelled at the gunman to put down his weapon, to which he reportedly shouted in response, "Leave me alone please," in Spanish, Gemma recalled.

Gemma said her best friend, Amerie Jo Garza, was one of the 19 children killed in the massacre.

-ABC News' Matt Gutman and Olivia Osteen