An armed policeman at the Uvalde school massacre had an opportunity to shoot the gunman but missed his chance waiting for permission from a supervisor, according to a new report.

Two teachers and 19 children died after police waited more than an hour to storm Robb Elementary School when Salvador Rolando Ramos opened fire on 24 May.

Some of the 21 victims “could have been saved” if they had received faster medical attention, a review by Texas State University revealed on Wednesday.

The report, considering the police response to the tragedy, pointed to a string of blunders made before Ramos, 18, walked through an open school door carrying an AR-15-style semi-automatic rifle at 11:33 a.m.

A Uvalde Police Department (UPD) officer reported he was at the scene where Ramos crashed his truck before leaving the vehicle with the weapon.

“The UPD officer was armed with a rifle and sighted in to shoot the attacker; however, he asked his supervisor for permission to shoot.

“The UPD officer did not hear a response and turned to get confirmation from his supervisor,” the report continued.

More on Texas School Shooting

The review, conducted by the university’s Advanced Law Enforcement Rapid Response Training (ALERRT) programme said: “A reasonable officer would have considered this an active situation and devised a plan to address the suspect.”

The 26-page report was based on school video footage, police body cameras, testimony from officers on the scene and statements from investigators.

It also found when the officers were no better equipped to confront Ramos when they eventually entered the building at 12.50pm.

“Effective incident command” appears not to have been established between the various emergency services that responded, the report revealed.

The massacre has become the deadliest school shooting in the US since a gunman opened fire at Sandy Hook Elementary in Connecticut in 2012.

A teacher who survived the shooting vowed never to forgive the police for the delays in entering his classroom, where 11 children were killed.

Read more:
Chilling warnings before Salvador Ramos shot 21 people
Police instructor says officers showed failings in leadership and mindset

Arnulfo Reyes branded officers “cowards” for failing to save the students.

“After everything, I get more angry because you have a bulletproof vest. I had nothing. I had nothing. You’re supposed to protect and serve, there is no excuse for their actions,” Mr Reyes said.

More than 700 people were shot dead in 43 of the 50 US states two weeks after the school shooting, according to data released in June.