During a press conference on Thursday, Phoenix police released a 13-minute video which showed members of the far-left militant group, also known as antifa, throwing objects at officers — including gas canisters filled with an unknown substance.
Officials say the gas was thrown at them before officers determined that use of force was necessary to mitigate the incident.
“This is not ours. We do not have gas that looks like this or reacts like this,” police spokesman Sergeant Jonathan Howard said.
In response, police then threw pepper balls at the ground near protesters but the chaotic situation continued to worsen and masked people dressed in black threw water bottles and other projectiles at police.
Howard explained that police would not have deployed gas behind their lines, especially before officers had a chance to put masks on to protect themselves. Because the gas was unidentified, it quickly escalated to a safety and health concern.
“This is a gas that we do not know and we do not know its effects on the community,” Howard said.
Activists say police used unnecessary force and injured peaceful protesters. However, Howard said officers only aimed to disrupt the small group of agitators who were throwing items at police.
A police review board is investigating.
Dozens of protesters, angry with the police response, denounced officers actions at a city council meeting which lasted nearly six hours on Wednesday night.