Police face questions over delays storming Texas school

The motive for the attack remained under investigation, with authorities saying Ramos had no known criminal or mental health history.

Senator Ted Cruz, right, and Uvalde County Sheriff Ruben Nolasco pray during a vigil in Uvalde following the shooting at Robb Elementary School (Jae C Hong/AP)

Law enforcement agencies were facing questions and criticism over how much time elapsed before they stormed a Texas primary school classroom and put a stop to the rampage by a gunman who killed 19 children and two teachers.

Investigators were also unable to say with any certainty whether an armed school district security officer outside Robb Elementary in Uvalde had exchanged fire with the attacker, 18-year-old Salvador Ramos, when he first arrived on Tuesday.