Amid two years of painful wrangling over the delayed police response to the deadly shooting at Robb Elementary School in Uvalde, Texas, the role of the federal agents who finally breached the classrooms and killed the gunman has largely avoided scrutiny.

The agents, from U.S. Customs and Border Protection, were seen as having saved the day by responding to the school and stepping in after a 77-minute delay.

But a 203-page report released on Wednesday by the agency complicated that simple narrative, finding that the border agents had been just as confused and delayed as dozens of other state and local law enforcement agents inside the school by the chaotic and mostly leaderless response.

The report, from the agency’s Office of Professional Responsibility, also offered the most detailed account yet of the tense and violent moments when federal agents finally entered the classrooms and the gunman burst from a closet and began firing at them.

And despite the agents’ central role in confronting and killing the gunman, the report raised questions about whether the dozens who responded had the legal authority to do so. The agents were insufficiently trained in responding to active shooter situations, the report found.

Its recommendations included that the agency take steps to better train its officers in active shooter responses, particularly to those in which breaching a door may be necessary, and to seek to clarify the law around how the agency interacts with state and local law enforcement during such events.