Apple Valley, California - The San Bernardino County Sheriff's Department has released new footage of a deputy's fatal shooting of Ryan Gainer while the Black teen was experiencing a mental health episode.

Gainer, who has autism, died after San Bernardino officers fatally shot him last Saturday following a 911 call reporting a dispute at the family home. The sheriff's office faced backlash for only releasing partial body cam footage of the incident, omitting the actual shooting.

The sheriff's office on Wednesday followed up with additional video showing the 15-year-old running out of his home carrying a gardening tool.

A deputy raises his gun and warns Gainer to stop. He runs backwards and then pulls the trigger as the teen continues to move toward him.

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Sheriff Shannon Dicus said during a Wednesday press conference that it appeared both deputies on the scene had fired their guns.

"Why would you do that? Why would you shoot my baby?" a distraught family member, likely Gainer's mother, can be heard saying in the video.

The family later said Gainer was acting out after a dispute over household chores.

The video shows police waiting around a minute before approaching Gainer, who is lying on the ground, to provide medical attention.

Dicus said his department had been to the Gainer home five times this year, and that the teen had previously been transported to a mental health facility without the use of force.

Nevertheless, Dicus defended the deputies' actions, saying, "We need to understand in this circumstance, whether we knew, didn't know, had the best resources available to us – this is a reactionary time. And if we're looking at this in the scope of being a human being and what they're trained for, the deputies followed through in what their training protocols are."

The killing has reignited demands for greater investments in mental health care and social services, noting that militarized police should not be responding to mental health calls like Gainer's.

The Gainer family has started a GoFundMe to help cover Ryan's funeral expenses.