Police arrested 74 people at a Black Lives Matter demonstration in Rochester, New York, on Friday amid nationwide protests against police shootings of black citizens.
The Rochester demonstration was one of many held in the wake of deadly police shootings in Baton Rouge, Louisiana, and suburban St. Paul, Minnesota, and came after the sniper attack that killed five police officers in Dallas.
Officials said they had made attempts to communicate with organizers and thought the protest was ending before the arrests were made.
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"We actually started demobilizing officers and ... arranging for some officers to be in the area just to keep an eye on things," Rochester Police Chief Michael Ciminelli said at a press briefing early Saturday.
Officers donned riot gear "later on" and at one point the crowd began to surround them and rocks were thrown, he said.
"At this point ... there were 74 arrests for disorderly conduct. There were also two charges for resisting arrest," he said. The crowd numbered more than 400 people, he said.
At the same briefing, Rochester Mayor Lovely Warren said the situation had "escalated a little bit" but police did not have to use use any pepper spray, batons or "deploy any weapons, any tasers."
Two journalists were also mistakenly arrested.
"I apologize for that. They were there trying to do their job to cover this event," Ciminelli added. Warren also apologized to the journalists.
Nobody was injured during the night, Ciminelli said without going into very much detail about the circumstances around the detentions.
The "74 arrests made it's difficult for us to break down each individual one," he added.
In spite of the number of detentions, Ciminelli said the department "didn't blindly make arrests."
Earlier, Ciminelli said he would have preferred not to have the rally in the city on Friday, a day after the Dallas massacre. However, he said, if people wanted to gather and voice their concerns, "we will protect them in doing so."