Uvalde, Texas school shooting timeline: How the massacre at Robb Elementary unfolded

UVALDE, Texas - Authorities investigating the Robb Elementary School shooting in Uvalde, Texas, have updated the timeline of events that led to the massacre of 19 children and two teachers.

Texas Department of Public Safety Director Steven McCraw said Friday that nearly 20 officers were in a hallway outside of the classrooms for more than 45 minutes before agents used a master key to open a door and confront the gunman, Salvador Ramos. 

The on-site commander believed the gunman was barricaded in a classroom at the school during Tuesday's attack and that the children were not at risk.

"Of course it was not the right decision. It was the wrong decision," McCraw said.

RELATED: Texas official: Kids repeatedly called 911 asking for help during school shooting

A student inside the classroom repeatedly called 911, at one point pleading to "please send the police now."

Timeline of shooting

Here’s a timeline of events that led to the shooting, according to the Texas Department of Public Safety:

• 11:27: The exterior door where the shooter entered the school was propped open by a teacher.
• 11:28: Ramos crashed a vehicle into a ditch. At that time, a teacher ran to room 132 to get a phone, then walked back to the exit door that remained propped open. There were two males at a nearby funeral home who approached the crash scene, but they ran when Ramos began shooting at them. That’s when the teacher called 911 from inside the school and said there was a crash and a man with a gun.
• 11:31 Ramos reached the last row of vehicles in the school parking lot and began shooting at the school while patrol vehicles arrived at the funeral home.
• 11:33: Ramos entered the school and began shooting into room 111 or room 112. He shot more than 100 rounds at that time.
• 11:35: Three Uvalde police officers entered the school using the same door as Ramos. They were followed by another four officers from the Uvalde PD, along with a deputy sheriff. At that time, there were seven officers on scene. The first three who arrived went to the door, and two were grazed with bullets while the door was closed.
• 11:37: Another 16 rounds were fired inside the classroom.
• 11:51: More police and U.S. Border Patrol agents arrived.
• 12:03: There were as many as 19 officers in the hallway at this time.
• 12:15: A Border Patrol tactical team arrived with shields. 
• 12:21: Ramos fired more shots, believed to be at the door. At this time, law enforcement moved down the hallway. It would be another 30 minutes before they entered the classroom.
• 12:50: Officers got a set of keys from a janitor, unlocked the classroom door and then killed Ramos.

Timeline of 911 calls from inside the classroom

McCraw also gave a timeline of the multiple 911 calls made from inside the classrooms. He warned: "It’s better that I read it to you than you listen to it."

• 12:03: A student inside room 112 called 911. The call lasted 1 minute and 23 seconds.
• 12:10: The same student called back and said multiple people were dead.
• 12:13: She called again.
• 12:16: The student called 911 again and said eight or nine students were alive.
• 12:19: Another student called 911 from room 111. She hung up when another student told her to.
• 12:21: Three shots were fired and heard on a 911 call.
• 12:36: The original student called back. She was told to stay on the line and be quiet.
• 12:37: The child asked 911 operators to send police.
• 12:46: The student said she could hear police next door.
• 12:50: Shots were fired.
• 12:51: The 911 call got loud, and it sounded like officers were moving children out of the classroom. At that time, the first child who called was brought outside and the call was cut off.

The Associated Press contributed to this report.