The video shows the transgender assailant, Audrey Hale, shooting the school’s doors to gain access.
Nashville police have released video of the moment an attacker entered a school before shooting six people dead, including three nine year-olds.
Audrey Elizabeth Hale was shot dead after being confronted by police at the private Christian school.
Hale, 28, who identified as transgender, was described by officials as a “lone zealot”, who lived in Nashville, and was armed with two assault-type weapons, and a handgun.
Hale had a manifesto and detailed maps of the school, and entered the building by shooting through its doors before the killings.
The video shows the doors’ panes smashing into smithereens as Hale makes their way in.
Hale is shown wandering the school premises holding the rifle.
Police chief John Drake said: “We have a manifesto. We have some writings that we’re going over that pertain to this day, the actual incident. We have a map drawn out about how this was all going to take place.”
The six victims have been named as Evelyn Dieckhaus, Hallie Scruggs, and William Kinney, all aged nine, 61-year-olds Cynthia Peak and Mike Hill, and 60-year-old Katherine Koonce who was the school’s headteacher.
Officers started receiving reports of an attack at 10.13am (4.13pm UK time) and as police began clearing the ground floor of the school they heard gunfire coming from the second floor.
Two officers from a five-member team opened fire in response and fatally shot the suspect at 10.27am (4.27pm).
The three children, who were all students, were pronounced dead after they arrived at hospital.
The attacker died after being “engaged by” officers, police said in a Twitter post.
A possible motive for Hale’s gun violence is not known.
Vigils are under way, as Nashville residents left flowers, balloons and other tributes to the victims at the school.