The surveillance film shows Salvador Ramos crashing his pickup truck outside Robb Elementary School and then entering the building with a semi-automatic rifle.
Then you hear the sound of a shooting going on for more than two minutes.
Several minutes later, the police are seen arriving at the school.
They then take shelter at the end of a corridor adjacent to the two classrooms where the shooting takes place.
Then it will take another 77 minutes before the police storm the premises.
Sharp criticism of the police
Texas Gov. Greg Abbot initially praised the police for handling the shooting, saying they had shown "fantastic courage."
He later admitted that he had been misled regarding the police response.
Since the incident, police have received harsh criticism, especially for waiting more than an hour before confronting Ramos.
- The video is deep, deeply disturbing.
That they had to wait for over 70 minutes is heartbreaking, and I think it is indefensible, a senator from Texas told Reuters.
The victims' families are upset
The publication of the video has upset the families of the victims.
State Security Chief Steven McCraw wrote on Twitter that he was "deeply disappointed" by the newspaper's decision to publish the video and that family members of the dead and injured should have seen it first.
The Austin American-Statesman says that the video was published with the aim of "continuing to pay attention to what happened at Robb Elementary School, something that families and friends of the victims have long demanded," writes Reuters.