Shock new Texas shooting timeline reveals how long Salvador Romas was in school before he was gunned down

THE Texas shooter was inside Robb Elementary school for an hour before he was gunned down, police have revealed.

Salvador Ramos, 18, was not confronted by officials before entering the school to unleash the massacre that left two teachers and 19 students dead on Tuesday.

He entered the school through a door that was unlocked, Texas authorities said on Thursday.

Officials added that they're still investigating why the door was unlocked.

On Wednesday, Governor Greg Abbott revealed how Ramos made his way into the elementary school.

After going through the backdoor, the gunman then went through a sliding door that connected the empty room to another classroom, where the carnage unfolded.

Abbott also revealed that 30 minutes before the school shooting unfolded, Ramos, posted: "I'm going to shoot my grandmother."

In a follow-up post, he wrote: "I shot my grandmother," according to Abbott.

Less than 15 minutes later, Ramos posted: "I'm going to shoot an elementary school," the Texas governor said during Wednesday's press conference.

Ramos was reportedly a high school dropout with no known criminal or mental health history.

Lt. Christopher Olivarez of the Texas Department of Public Safety told  on Wednesday that all the victims were in the same fourth-grade classroom.

Olivarez said the Ramos barricaded himself inside the classroom, “shooting anyone that was in his way."

As the suspect shot at responding police officers, authorities were going around the campus, breaking windows and trying to evacuate children and staff.

They were then able to force entry into the classroom where the shooter was.

VICTIMS NAMED

So far, 17 of the 19 kids have been identified by loved ones - they are students Amerie Jo Garza, Xavier Lopez, Uziyah Garcia, Makenna Lee Elrod, Ellie Garcia, Eliahana 'Elijah Cruz' Torres, Annabell Guadalupe Rodriguez, Tess Marie Mata, Lexi Rubio, Nevaeh Bravo, Rojelio Torres, Jayce Carmelo Luevanos, Jailah Nicole Silguero, Miranda Mathis, Jose Flores, Maite Yuleana, Jackie Cazares, and Alithia Ramirez.

The children killed were aged between seven and 11.

Amerie's grandmother Berlinda Irene Arreola told  that the gunman reportedly told students that they were going to die.

Amerie was shot dead as she tried to call 911 and her best friend was reportedly left covered in blood.

Arreola said: “She had her phone, and she called 911, and instead of grabbing it and breaking it or taking it from her, he shot her.”

She added Amerie died a hero because she tried to call the emergency services.

Amerie had just received an award for getting on the A-B honor roll.

The shooting became the worst elementary school massacre since Sandy Hook in 2012.

It surpassed the number of dead in the Marjory Stoneman Douglas High School shooting, which left 17 teens dead and 17 others injured on Valentine's Day in 2018.