A police officer responding to the May 24 mass shooting at Robb Elementary School in Uvalde reportedly had the chance to shoot the gunman before he got inside the school, a report from The New York Times revealed Friday evening.

One of the first officers on the scene had an AR-15 but did not want to risk harming children by attempting to take down the gunman, a senior sheriff’s deputy told the NY Times.

More from the NY Times:

The fateful decision, which has not been previously reported, represented the second missed opportunity for officers arriving at Robb Elementary School to prevent a massacre by intervening while the gunman was still outside the school. Officials have said that an officer from a different department, the Uvalde school district police force, arrived early but drove past the gunman, not seeing him in the parking lot of the school.

The quick arrival of several officers on May 24 reflected the speed with which the initial response took place, and contrasted sharply with what would become a protracted delay in finally confronting the gunman after he began shooting inside a pair of connected fourth-grade classrooms.

The short-lived opportunity is another detail that helps explain what happened that day, which ended in 19 students and two teachers being killed. Officers did not respond inside the physical school building until nearly an hour-and-15-minutes after the shooter entered it; he was ultimately taken down by a Border Patrol tactical team and not local law enforcement, as we previously reported.

Local police are now working with state investigators to get a clearer picture of what went wrong throughout the situation, NBC News reported Friday. Everything from the timing of 911 calls to Uvalde CISD Police Chief Pete Arrendondo’s actions is being heavily scrutinized.