The law enforcement response to the Uvalde school shooting that killed 19 children and two teachers was “an abject failure” in which a commander put the lives of officers over those of the children, Texas Department of Public Safety Director Steven McCraw says.

During a Texas Senate hearing into the May 24 mass shooting, Mr McCraw told lawmakers that “terrible decisions” were made by the onsite commander and officers who responded to the scene did not have enough training, costing them valuable time that may have saved lives.

“There is compelling evidence that the law enforcement response to the attack at Robb Elementary was an abject failure and antithetical to everything we’ve learned,” Mr McCraw said.

Police actions after the gunman entered Robb Elementary School and began shooting have come under close scrutiny, with many parents and relatives expressing deep anger over the response.

Among the delays Mr McCraw detailed was the search for a key to the classroom door where the shooting occurred.

He said police waited to enter while they sought a key, despite the fact that the door was not locked and there is no evidence officers ever tried to see if it was secured.

“There’s no way to lock the door from the inside and there’s no way for the subject to lock the door from the inside,” Mr McCraw said.

The Texas DPS, days after the shooting, said that as many as 19 officers waited over an hour in a hallway outside classrooms 111 and 112 before a US Border Patrol-led tactical team finally made entry.

Mr McCraw reiterated that in the hearing on Tuesday.

“The officers had weapons, the children had none. The officers had body armour, the children had none. The officers had training, the subject had none. One hour, 14 minutes, and eight seconds – that is how long the children waited, and the teachers waited, in Room 111 to be rescued,” the DPS director said.

“Three minutes after the subject entered the west building, there was a sufficient number of armed officers wearing body armour to isolate, distract and neutralise the subject,” Mr McCraw added.

“The only thing stopping a hallway of dedicated officers from entering Room 111, and 112, was the on-scene commander, who decided to place the lives of officers before the lives of children,” the director said in the hearing.

Mr McCraw said the scene commander, Uvalde schools police chief Pete Arredondo, “waited for radio and rifles, and he waited for shields and he waited for SWAT. Lastly, he waited for a key that was never needed”.

Mr Arredondo said earlier this month that he never considered himself the incident commander of the scene of the shooting and that he did not order police to hold back on breaching the building.

The killer took firearms to Robb Elementary School in Uvalde, Texas.

Mr Arredondo told the Texas Tribune that he left his two radios outside the school because he wanted his hands free to hold his gun.

He had said he called for tactical gear, a sniper and keys to get inside, holding back from the doors for 40 minutes to avoid provoking sprays of gunfire.

Community members along with parents of the victims urged Arredondo to resign during an impassioned school board meeting on Monday, ABC News reported.

-AAP