A teenager fatally shot in an East Texas police station lobby was killed after she lunged at an officer with a butcher knife and a Taser failed to stop her, police said Wednesday

Longview Police Chief Don Dingler and spokeswoman Kristie Brian provided new details about last week's shooting of 17-year-old Kristiana Coignard and released video that shows the incident, including the girl scuffling with an officer shortly before he and another officer fire multiple shots at her.

The shooting has garnered attention amid increased scrutiny surrounding law enforcement's use of deadly force. Officials previously had not disclosed what type of weapon Coignard had and had refused to release the video, raising questions about what exactly happened and why police didn't use other means to subdue Coignard.

The video shows Coignard entering the Longview police station lobby and using the lobby phone. There is no audio, but Brian said she requested help but would not say why.

Officer Glenn Derr was the first officer to respond. When he approached the teenager, she held up her hand, which had "I have a gun" written on it, Brian said.

The video shows Derr struggling with the girl and trying to subdue her. At one point, the officer throws her to the ground. She's lying on the floor and Derr is kneeling, holding her down, when the officer suddenly gets up and steps back. Brian said Derr broke away when he saw Coignard reaching for a butcher knife in her waistband.

Officer Gene Duffie then arrives, followed by Officer Grace Bagley. Coignard is then seen charging at Derr. Brian said Duffie fired his Taser, then Derr and Bagley quickly followed with gunshots.

Dingler said the officers were justified in shooting the girl.

"All the patrol officers carry Tasers, plus expandable batons. I think you'll see from the video that the time was a factor. There was no time for the officers to use other means," Dingler said.

All three officers are on paid administrative leave while the Texas Rangers investigate, Brian said.

The girl's family has said she had mental health problems and have questioned why police had to shoot her.

Coignard was living with her aunt, Heather Robertson, in Longview, about 130 miles east of Dallas.

Messages sent to Robertson by The Associated Press were not returned Wednesday. She previously told the liberal political blog ThinkProgress that her niece had bipolar disorder and had twice attempted suicide, but was not violent toward anyone except herself.