Texas Department of Public Safety Director Col. Steven McCraw on Friday gave a detailed timeline of the mass shooting at Robb Elementary School on May 24 that left 19 children and two teachers dead.

Here are the key moments he laid out (all times are in Central Standard Time):

11:27 a.m.: Video shows that an exterior door to Ross Elementary School that gunman Salvador Ramos entered was propped open by a teacher.

11:28 a.m: Ramos crashes a vehicle near the school into a ditch, gets out and begins firing upon two people who came outside to see the crash near a funeral home. Civilians are not struck by gunfire. The teacher runs to a room to get a phone, returns to the door, and the door remains open. 

11:30 a.m.: The first 911 call is made to Uvalde police reporting a car crash and a man with a gun outside the school.

11:30 a.m.: The US Marshals Service says it received a call from a Uvalde police officer requesting assistance.  

11:31 a.m.: The shooting suspect reaches the last row of cars in the school parking lot and shooting begins outside of the school. Patrol vehicles reach the funeral home, and a patrol car drives by shooter, who is hunkered down by another vehicle.

11:32 a.m.: The suspect fires at the school. 

11:33 a.m.: The suspect enters the school and begins shooting into a classroom. He shot more than 100 rounds.

11:35 a.m.: A total of seven officers are on the scene, and three officers enter the school, later followed by an additional team of three more officers and a sheriff. Two of the initial officers received grazing wounds from the suspect while the classroom door was closed.

11:37 a.m.: Sixteen rounds were fired from 11:37 a.m. to 11:44 a.m.

11:43 a.m.: Robb Elementary announces on Facebook that “Robb Elementary is under a Lockdown Status due to gunshots in the area.”

11:51 a.m.: More officers arrive.

12:03 p.m.: As many as 19 officers are in the school’s hallway. 

12:03 p.m.: A girl in room 112 of the school makes a 911 call.

12:10 p.m.: A 911 call is received from the same girl in room 112, reporting multiple people are dead.

12:13 p.m.: The girl makes another 911 call.

12:15 p.m.: Border Patrol’s tactical unit BorTac team arrives on scene.

12:16 p.m.: The same girl makes another 911 call, reporting there were “eight to nine students alive.”

12:17 p.m.: Robb Elementary announces on Facebook: “There is an active shooter at Robb Elementary. Law enforcement is on site. Your cooperation is needed at this time by not visiting the campus. As soon as more information is gathered it will be shared. The rest of the district is under a Secure Status.”

12:19 p.m.: A different 911 call is received from a caller in room 111, but the caller hung up after another student told them to.

12:21 p.m.: Suspect fires again.

12:21 p.m.: Another 911 call is received, and three shots fired are heard.  

12:21 p.m.: Officers move down the hallway.

12:36 p.m.: There is a 911 call that last 21 seconds, with a student saying, “he shot the door.”  

12:43 and 12:47 p.m.: 911 caller says “please send police now.” 

12:46 p.m.: 911 caller can hear police next door.

12:50 p.m.: Shots are heard being fired over the 911 call.

12:50 p.m.: Law enforcement breach door using keys from janitor and kill suspect. 

12:51 p.m.: On 911 call, it sounds like officers are moving children out of the room.