The suspected gunman who slaughtered 19 students and two teachers Tuesday at a Texas elementary school fired shots outside the school for 12 minutes before entering, an official said.

Eighteen-year-old Salvador Ramos spent approximately 12 minutes outside of Robb Elementary School firing shots before he walked into the school and barricaded himself in a classroom, Regional Director for the Texas Department of Public Safety, Victor Escalon, said Thursday, according to The Wall Street Journal (WSJ).

Escalon was unable to provide any answers Thursday as to why no one stopped Ramos from entering the school, the WSJ reported.

A rough timeline of Tuesday’s deadly shooting began around 11:28 a.m. when Ramos crashed his truck into a ditch near the school, Escalon said, according to the WSJ. Witnesses began calling authorities around 11:30 a.m., after Ramos began firing at people at a funeral home across the street from the school, according to the report. Ramos reportedly then walked onto school grounds before walking inside the school without being confronted by anyone at 11:40 a.m.

Authorities arrived on scene roughly four minutes later, according to the WSJ. Shots were exchanged between police and Ramos, according to the report. (RELATED: ‘We Had No Idea This Was Goodbye’: TX Sheriff Attended Honor Roll Ceremony For Daughter Who Died Hours Later In Shooting)

A Border Patrol tactical team entered the school roughly an hour later at 12:40 and killed Ramos, according to the WSJ.

State authorities, including the Texas Rangers, are investigating the Uvalde Police Department amid concerns and questions that officers did not respond quickly enough. Officers were present throughout the attack, with many standing in the parking lot during the 30-60 minute period in which Ramos opened fire. Authorities did not breach the classroom until a staff member gave them a key to unlock the door, the Associated Press (AP) reported.

BREAKING: Authorities now confirm they are examining the response of police in Uvalde in the shooting of 19 children amid conflicting witness statements, including what steps they took to stop the gunman. Part of the review will include a timeline based on radio traffic. (1/3)

— Tony Plohetski (@tplohetski) May 26, 2022

Video showed distraught parents and onlookers begging authorities to rush into the school and subdue Ramos to no avail, with one father suggesting he and others just rush the school themselves.

Authorities also gave conflicting reports about whether officers engaged with Ramos as he entered the school.

Several reports place Ramos in the classroom between 30-60 minutes after law enforcement engaged him but failed to keep him out of the school. Local authorities said agents had “pinned” or “contained” Ramos during the time period and protected the rest of the school despite the fact that Ramos was “contained” in a classroom full of children that he later killed.