The actions of a school district police chief and other law enforcement officers are at the center of the investigation into this week's shocking school shooting in Uvalde, Texas. Authorities acknowledged Friday that children and teachers repeatedly begged 911 operators for help while the police chief told more than a dozen officers to wait in a hallway at Robb Elementary School. The delay in confronting the shooter — who was inside the school for more than an hour — could lead to discipline, lawsuits and even criminal charges against police.

The actions — or more notably, the inaction — of a...