Crowd control tactics of Portland's police officers are once again under scrutiny following a rally downtown Sunday.

A video that's gone viral appears to show a police officer at the rally throwing a crowd control grenade directly at a documentary filmmaker, possibly hitting people before the device exploded on the ground.

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The following video shot by Paul Kachris-Newman contains sensitive language.

Cop threw flash at me. He aimed for unmasked independent press. No warning. Deliberate. Hit camera/chest. Reckless and dangerous. Fire him. pic.twitter.com/jIWNg4Njz7 — Village to Village (@v2vfilm) September 12, 2017

The officer was standing in Lownsdale Square near the corner of Southwest Salmon Street and Third Avenue, just across the street from the Mark O. Hatfield U.S. Courthouse.

The device was actually a "rubber ball distraction device," according to police. It's similar to a flash-bang grenade. Both create a loud bang. But rather than a loud noise followed by a flash of light, the distraction device used Sunday exploded and projected rubber balls.

In the video — shot Sunday as anti-hate group protesters marched downtown — the male officer stands between protesters and fellow police officers who are on the ground making arrests. The officer reaches for the device on his vest and then turns his back to the crowd filming the incident. A moment later, the officer turns to face the camera and appears to throw the device underhand at the documentary filmmaker, later identified as Paul Kachris-Newman.

Another video of the same incident taken from a wider angle shows a protester next to Kachris-Newman throwing what appears to be a wooden spoon at the police officer before the officer deploys the device.

A third video catches yet another angle, this time from the side. It shows what appears to be the wooden spoon landing several feet short of the officer who threw the grenade. Police say the spoon hit a different officer.

The following video shot by Doug Brown of the Portland Mercury contains sensitive language.

Various versions of the video spread widely on social media in the days after the incident, with critics saying the device did not need to be used and that police overreacted.

The Portland Police Bureau said it's reviewing the encounter.

While it is not clear yet what prompted the officer to use the device, the videos do show the tense environment officers and protesters were in — as well as the high level of scrutiny police decisions can come under when force is used at a largely peaceful protest.

Police say in addition to the wooden spoon, two other items hit officers during the filmed incident before the distraction grenade was used. At least one officer was injured when a thrown water bottle hit him in the face during the moments captured in the videos. A second officer suffered a twisted ankle at the protest, but it is not clear if it happened in the same incident.

Kachris-Newman said he sees multiple ways the videos might be interpreted.

Related: Students, Toddlers, 'Raging Grannies' Protest Right-Wing Patriot Prayer Rally

"It's kind of like a Rorschach test, you're going to be able to read this situation in a lot of different ways," he said.

Kachris-Newman said he felt the officer was throwing the canister at him, rather than trying to use the grenade to establish a perimeter.

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A 2015 investigation by ProPublica found flash-bang grenades are used by law enforcement with little oversight and can cause serious burns and other injuries. Because of dangers to both officers and people in the area, some police departments have dramatically curbed their use.

Kachris-Newman said he was at the rally to gather footage for an upcoming documentary, not as a protester. He said it was a tense environment from almost the beginning.

"I always try and remain mindful of a safe distance," he said. "I'm typically not the closest camera operator. And if I'm asked to move at all, I do that. So I was getting as close as I could, because I realized that the person being arrested — it looked like a particularity aggressive situation."

Portland Police arrest a young woman at a protest on Sept. 10, 2017. Ericka Cruz Guevarra / OPB

The officer was surveying the perimeter, Kachris-Newman said. The officer looked at him, looked away and then turned back to Kachris-Newman.

"In a matter of less then a second [the device] ricocheted off myself onto a counter-protester and then onto the ground," Kachris-Newman said.

Videos from different angles make it harder to tell if the device hit Kachris-Newman first or a masked person standing nearby.

Kachris-Newman was backing away quickly when the flash grenade exploded.

"It was quite loud," he said. "I had trouble hearing for the rest of the day."

Regardless of the officer's reasoning, Kachris-Newman said he was frightened.

"I've never had anybody throw something that I was under the impression would explode or detonate toward me," he said.

Kachris-Newman said he understands that there's some implied risk in attending what is sure to be a tense protest, particularly when past events have resulted in isolated incidents of violence and vandalism.

Related: Police Struggle To Balance Public Safety With Free Speech During Protests

Kachris-Newman said he knows police have a difficult job, but also that "public servants should be held accountable when they fail to meet their own expectations."

He said he posted his video because he believes the officer was negligent and made a "poorly constructed move."

"There are more appropriate ways to, I believe, regulate nonviolent observers," Kachris-Newman said. "And if employing a flash canister was indeed necessary, I don't know if there's ever an appropriate time for it to be thrown towards individuals.

"I feel like that cannot be something that we let slide without a broader conversation about it."

Portland's Independent Police Review has opened an investigation into how Sunday's rallies were handled. Portland Police Bureau spokesman Sgt. Christopher Burley said "officers had taken several projectiles" before the flash grenade was tossed.

"As reports are compiled and a review process proceeds, I will have a more complete understanding of what protestor actions the officers were reacting to," Burley said in an email.

Speaking on OPB's Think Out Loud on Thursday, Portland Mayor and Police Bureau Commissioner Ted Wheeler said he supports the actions of officers, but added that police can always strive to do better.

"I am not going to get suckered into making a definitive statement about a YouTube video," Wheeler said. "I saw videos of varying length, from varying angles and they told different stories depending upon the angle and depending on what people chose to show on their YouTube channel."

This story has been updated to include a more thorough response from the Portland Police Bureau and updated comments from Mayor Wheeler.