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The FBI will conduct an independent investigation in the case involving a sheriff's deputy who shot and killed a teenager carrying a replica assault rifle, the Sonoma County Sheriff's Office announced Friday.

Thirteen-year-old Andy Lopez was shot seven times on a Santa Rosa sidewalk Tuesday by Sonoma County sheriff's deputies who said they thought the boy’s fake weapon was a real AK-47 assault rifle.

“The Sheriff will cooperate fully with the FBI and welcomes their participation,” Sonoma County Sheriff Steve Freitas said in an email statement.

MORE: Sonoma County Deputies Shoot, Kill Boy Carrying Replica Assault Rifle

The officers involved previously said they pulled over, took cover and ordered Lopez to "put the gun down." One of the deputies told investigators he believed the boy was going to shoot at him or his partner so he fired several rounds.

Santa Rosa police have released a detailed timeline of the shooting Thursday.

Many in town, including Andy's parents, are insisting that Andy was the type of boy who would listen to police. But other witnesses also said they heard police order the boy to drop his weapon.

Hundreds in the Santa Rosa community, many of them teenagers, continue to express their frustration over what they are calling police brutality.

“Obviously there is no justice that can compare to a little boy dying,” Jessica Serratus said. “At least fire the cops, put them in jail, do something.”

MORE: Retired Cop Says Officers Have to Assume Guns Are Real

Hundreds of teenagers gathered for a rally at Santa Rosa City Hall on Friday morning before walking a few miles to the sheriff’s office, where the doors were locked.

“I am here to support Andy’s family, and just anybody who has lost a child deserves some support,” Chelsea Weeks said.

Though the sheriff’s office was closed, there were deputies inside. County officials were also at the rally, observing, but said they had no comment.

In Friday’s email, Sheriff Freitas thanked “the community for how peaceful and respectful the memorials and protests have been in the aftermath of this incident. The Sheriff continues to express his sympathy to the Lopez family and the community.”

On Sunday afternoon, a public viewing was held for Lopez. It started at 2 p.m. at a private mortuary in Windsor. Crowds of people turned out to pay their respects to the 13-year-old boy.

"It is wrong," Lopez's friend Arianna Barragan said. "Sheriffs take advantage of their jobs, and he didn't deserve to die. And a lot of people are angry about it because they know Andy would have put his gun down."