It’s unclear what exactly transpired in the time between when Salvador Ramos crashed a pickup outside Robb Elementary in Uvalde, Texas, to when he was killed 90 minutes later. Since Tuesday — when the 18-year old gunman killed 19 children and two teachers — state and local law enforcement officials have provided a steady stream of conflicting information about the police response to the mass shooting, leaving mourning families and a frustrated public furious and seeking answers.

On Friday, Texas Department of Public Safety Director Steve McCraw gave the most detailed account yet of the rampage at the school, but plenty of questions still remain. The most notable of which is why the Uvalde police, the Uvalde school district’s police, and, later, a tactical unit from the border, were all on the scene and yet refrained from moving to neutralize the gunman until it was too late. Below is a breakdown of what law enforcement has and hasn’t disclosed.

What happened outside the school? 

Texas Department of Public Safety officials have said that the gunman shot his grandmother in the face and then stole her pickup truck, which he then wrecked in a ditch near the school at 11:28 a.m. local time. The grandmother, Celia Martinez Gonzalez, survived and is in stable condition. The first 911 call from the scene came in at 11:30. Witnesses say Ramos got out the passenger side of the truck with a long gun and a bag. TDPS Deputy Victor Escalon said on Thursday that Ramos then fired at two witnesses across the street at a funeral home before climbing a fence to get into the parking lot of the school.

McCraw clarified on Friday that the witnesses approached the truck after it crashed, and fled after seeing Ramos, who fired at them.

Ramos then began shooting into the school. Officials said earlier this week that an armed school safety officer engaged — and even fired at — Ramos, but Escalon said on Thursday that this was not the case, and that Ramos “was not confronted by anybody” before entering the school through a door that “appears” to have been unlocked. 

McCraw said on Friday the door had been left propped open by a teacher.

An armed school safety officer who was not on the scene responded to the 911 call, but drove past Ramos, who was “hunkered down” behind a vehicle in the school’s parking lot, according to McCraw. Escalon said on Thursday that Ramos entered the school at 11:40, and was unable to answer questions about what transpired during the apparent 12-minute gap between when he crashed the vehicle and when he entered the school.

McCraw said on Friday that Ramos actually entered the school at 11:33.

What happened inside the school?

McCraw said that once inside the school Ramos fired more than 100 rounds, based on audio evidence. Escalon said Ramos “barricaded” himself in a classroom. He was unable to clarify how exactly Ramos had barricaded himself inside the room. McCraw said on Friday that he had simply locked the door.

McCraw said that three Uvalde Police officers entered the school at 11:35, two minutes after Ramos entered the school (Escalon said on Thursday that it took four minutes). They were followed by three more officers and a county sheriff. Two of the initial three officers were grazed by bullets Ramos fired through the wall, leading them to retreat.

There was more gunfire, and by 11:51 more officers began to arrive. Just after noon, there were as many as 19 officers in the hallway, according to McCraw. They did not breach the door despite continuing to hear gunshots from the room, where officials have said they believe most, if not all, of the 21 victims were killed.

McCraw noted that people were calling 911 — including students — from inside the classroom. One caller at 12:15 described eight or nine children still being alive. “Please send the police now,” another said.

It wasn’t until 12:50 that the Border Patrol’s Tactical Unit (BORTAC), breached the door and killed Ramos. They got the janitor to give them a key.

What were the cops doing?

BORTAC entered the classroom at 12:50, but they arrived at the scene 35 minutes earlier, at 12:15, raising perhaps the most consequential question of the massacre:

Why didn’t they go in sooner?

The New York Times reported on Friday, citing officials briefed on the situation, that Uvalde Police — which was working to secure a perimeter and evacuate people from other parts of the building — prevented BORTAC from entering the school. An official told the Times that BORTAC did not understand why they were asked to wait, nor why BORTAC was called up from the border when the Uvalde PD’s SWAT team could have responded. McCraw said on Friday that the SWAT team is only part-time.

McCraw confirmed on Friday that BORTAC was told by local police to hold back, with the on-scene commanding officer, Uvalde ISD Police Chief Pete Arredondo, believing it to be “a barricaded subject situation.” The alternative would have been to consider it an active-shooter situation, which McCraw explained would have required every officer to “go and find where those rounds are being fired” before securing a perimeter or waiting for reinforcements.

It wasn’t deemed as such, though. “Hundreds of rounds were pumped in four minutes into those two classrooms,” McCraw said, with the belief being that everyone was dead and Ramos was at that point only trying to hold off law enforcement. It’s unclear why this was thought to be the case, considering the 911 calls describing the situation in the classroom and pleading for the police to do something.

“Obviously, based on the information we have, there were children in that classroom that were still at risk,” McCraw conceded. “From the benefit of hindsight where I’m sitting now, of course it was not the right decision. It was the wrong decision. Period.”

Witnesses have described a chaotic scene outside of the school, with bystanders pleading with law enforcement to go into the building and stop the carnage.

“Go in there! Go in there!” women shouted, according to one witness who spoke to the Associated Press. Javier Cazares, whose daughter Jacklyn was killed, said he suggested others rush the building. “Let’s just rush in because the cops aren’t doing anything like they are supposed to,” he said. “More could have been done.”

The Wall Street Journal reported that Angeli Rose Gomez was put in handcuffs for pleading with officers to go into the school. She said she convinced someone she knew on the Uvalde police force to get her set free, after which she hopped a fence and went into the school and retrieved her two children. “The police were doing nothing,” she said, according to the Journal. “They were just standing outside the fence. They weren’t going in there or running anywhere.”

McCraw said on Friday that it was a mistake for law enforcement to refrain from taking on the shooter. Lt. Chris Oliverez of the TDPS defended the decision Thursday on CNN, arguing that officers couldn’t move on Ramos because they didn’t know exactly where he was in the school. “They could have been shot,” he said of the officers. “They could have been killed.”

Twenty-one people, including 19 children, were killed instead.