Police made a "bad decision" in delaying their intervention at the Uvalde school, a Texas public safety official admitted at a press briefing on Friday.

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“Looking back now, of course it was not the right decision. It was the wrong decision, period,” he said at a press conference, when asked about the much-criticized delay in the intervention of the police.

Nineteen officers at the scene waited for a Border Police intervention unit, about an hour after the shooter, Salvador Ramos, broke into the building on Tuesday.

They also waited for the school janitor to give them the keys to open the closed classrooms.