A damning report has found systematic failures among law enforcement were behind the botched response to a school massacre in Texas. 

The Texas House committee has released its report on how police responded when an 18-year-old gunman stormed Robb Elementary School, murdering 19 students and two teachers on May 24.

The investigation found despite nearly 400 officers from various law enforcement agencies arriving at the scene, it took more than one hour for the gunman to be confronted and killed.

A lack of leadership and a careless approach to decision-making reportedly created chaos at the scene.

While the report says most victims were shot dead before police arrived, some may have survived their injuries, had it not been for the lengthy delay for an intervention.

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

The findings of the investigation, which are considered the most complete account of law enforcement’s response yet, was released to family members on Sunday.