Texas school shooting: Why was the gunman active for an hour before officers entered the school?

ITV News Reporter Robert Moore with what we know about the emergency response

Details about the timing of events and the police response to the Texas school shooting remain murky, days on from the attack.

Investigations are ongoing into America's deadliest school shooting in a decade, but authorities are facing questions about their response - and the time it took to stop the shooter, as it emerged he was inside for an hour before authorities entered.

Nineteen children and two teachers were killed in the shooting on in Uvalde on Tuesday.

How long did it take for police to stop the shooter?

An official said on Wednesday anywhere between 40 minutes to an hour elapsed from when the shooter opened fire to when he was shot dead.

A department spokesperson said on Thursday that authorities were still working to clarify the timeline of the attack.

Later in the day, however, they confirmed the gunman was in the building for more than an hour before he was killed by law enforcement officers.

ITV News Reporter Robert Moore on the questions surrounding the police response

Texas Department of Public Safety spokesperson Travis Considine said Ramos entered Robb Elementary School and began his rampage at 11:40am on Tuesday.

A Border Patrol tactical unit began trying to get inside an hour later, and at 12:58pm, radio chatter noted he was dead.

The amount of time that elapsed has stirred anger and questions among family members, who demanded to know why they did not storm the place and put a stop to the rampage more quickly.

What else do we know?

Victor Escalon, a regional director at the Texas Department of Public Safety, said on Thursday that Ramos did not initially encounter any law enforcement officers when he entered Robb Elementary School.

The law enforcement official said the gunman entered the building "unobstructed" through a door that was apparently unlocked.

Robert Moore, reporting from Texas, said witnesses were reportedly shouting at the police to enter into the school to accost the gunman.