An autistic teen shot by police in Idaho when he was seen carrying a knife has died after being taken off life support.

The 17-year-old boy was fired at repeatedly by cops from the other side of a chain-link fence while he held the weapon, His family have said Victor Perez died Saturday after being taken off life support machine.

The teenager, who also had cerebral palsy, had been in a coma since the April 5 shooting, and tests on Friday showed he had no brain activity according to his aunt, Ana Vazquez. He had undergone several surgeries after being injured and doctors removed nine bullets and amputated his leg.

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Police in Pocatello, in the south east of Idaho, responded to a 911 call reporting an apparently intoxicated man with a knife was chasing someone in a yard. The person turned out to be Perez who was not intoxicated but walked with a staggered gait due to his disabilities, Vazquez said. His family members had been trying to get the large kitchen knife away from him.

Victor Perez, a 17-year-old autistic and non-verbal boy with cerebral palsy, was left in a critical condition (
Image:
GoFundMe)

Video taken by a neighbor showed Perez lying in the yard after falling over when four officers arrived and rushed to the fence at the edge of the yard. They ordered Perez to drop the knife, but instead he stood and began stumbling toward them.

Officers opened fire within about 12 seconds of getting out of their patrol cars and made 'no apparent effort' to de-escalate the situation. Vacquez said: "Everybody was trying to tell the police, no, no. Those four officers didn't care. They didn't ask what was happening, what was the situation. How's he going to jump the fence when he can barely walk?"

The shooting outraged Perez's family and residents in the neighborhood, leading 200 people to attend a vigil Saturday morning outside the Pocatello hospital where he was treated. Another crowd gathered outside the Pocatello City Hall on which also houses the police department.

Victor Perez was shot Saturday at his home in Pocatello, Idaho, shortly after police arrived (
Image:
NBC News)

Police snipers watched from a nearby rooftop during the protest, but no violence was reported. Many people held signs with phrases such as: "Do better, PPD" and "Justice for Victor," while passing cars honked in acknowledgment.

Vasquez said on Saturday: "Those police broke our family. There is no way to explain the pain that we are feeling right now. It's like our hearts are kind of empty - it's not full anymore."

Police on the other side of the fence at the scene of the shooting (
Image:
NBC News)

The names of the officers have not been released, but they were put on administrative leave. Decisions about whether charges should be filed against them will be made after an independent investigation by the Eastern Idaho Critical Incident Team

Bannock County Prosecutor Ian Johnson responded by email which said: "When that investigation is complete a report will be submitted for review. In a continued effort to ensure independent and objective consideration, said report will be reviewed by an agency outside of Bannock County."

Police shot the disabled youngster nine times in his back yard as he carried a knife (
Image:
NBC News)

Pocatello Mayor Brian Blad said in a statement: "We recognize the pain and grief this incident has caused in our community." He said the city was "addressing this matter with the seriousness and thoroughness it deserves and with the appropriate respect for the gravity of the situation. The criminal, external, and internal investigations regarding the officer-involved shooting are underway, which is why we cannot answer questions out of concern of interfering with or compromising the investigation."

An autopsy into the teen's death will be performed on Monday.