The city of Portland may hire an outside investigator to review crowd control tactics used by police at recent rallies, Mayor Ted Wheeler said Wednesday.

Wheeler announced the possible outside investigation in response to a resident who addressed the City Council to complain about Portland police officers' use of flash bang grenades against protesters.

"There is going to be an investigation of all the tactics used, including potentially an outside review," Wheeler said.

The so-called "less-lethal" devices seriously injured several counter-demonstrators at a recent rally organized by right-wing demonstrators from Washington State. They and fellow protesters have charged that police used unnecessary force against them and fired flash bangs unprovoked.

Wheeler, who as police commissioner is ultimately responsible for all city law enforcement, said Police Bureau officers face a tough task when directed to keep agitated protesters safe. He said Chief Danielle Outlaw also took it upon herself to launch and support a bureau investigation of its own tactics and suspend use of some less-lethal devices in the meantime.

-- Gordon R. Friedman

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