UVALDE, Texas (AP) Nearly 400 law enforcement officials rushed to a mass shooting at a Uvalde elementary school, but egregiously poor decision-making resulted in more than an hour of chaos before the gunman who took 21 lives was finally confronted and killed, according to a damning investigative report released Sunday.

The nearly 80-page report was the first to criticize both state and federal law enforcement, and not just local authorities in the South Texas town for the bewildering inaction by heavily armed officers as a gunman fired inside two fourth-grade classrooms at Robb Elementary School, killing 19 students and two teachers.

Altogether, the report and more than three hours of newly released body camera footage from the May 24 tragedy amounted to the fullest account to date of one of the worst school shootings in U.S. history. Some families blasted police as cowards and demanded resignations.

At Robb Elementary, law enforcement responders failed to adhere to their active shooter training, and they failed to prioritize saving innocent lives over their own safety, the report said.

The gunman fired approximately 142 rounds inside the building and it is almost certain that at least 100 shots came before any officer entered, according to the report, which laid out in detail numerous failures. Among them:

No one assumed command despite scores of officers being on the scene.

The commander of a Border Patrol tactical team waited for a bullet-proof shield and working master key for the classroom, which may have not even been needed, before entering the classroom.

A Uvalde Police Department officer said he heard about 911 calls that had come from inside the classroom, and that his understanding was the officers on one side of the building knew there were victims trapped inside. Still, no one tried to breach the classroom.