Just a few hours ahead of more planned protests Saturday over the killing of George Floyd in Minneapolis, officials in Arizona‘s two largest cities implored demonstrators to refrain from violence.

The mayors of Phoenix and Tucson said some protesters caused extensive and unnecessary property damage Friday night. In Phoenix, cleanup crews swept up broken glass in front of boarded-up doors and windows and used a power-wash to remove spray-painted messages on a building.

The Phoenix protest unfolded after a vigil for Dion Johnson, who was fatally shot Monday during an encounter with state trooper along a freeway. Around 15 downtown Phoenix buildings, including the Sandra Day O’Connor U.S. Courthouse, sustained broken windows, according to authorities. Protesters also slashed the tires of seven police SUVs and attempted to set one vehicle on fire. Two people were arrested.

Phoenix Mayor Kate Gallego, flanked by the police chief and community leaders at a news conference, said acts of violence and property damage committed by a few were unacceptable and weren’t helping protesters’ cause.

“We will not stand for this violence and destruction,” Gallego said. “This is our city, we love this city. We have to work together …”

Tucson Mayor Regina Romero issued a similar message at her own news conference.

“What I saw was not Tucson. And it’s not going to be what moves us forward. Violence only brings violence,” Romero said.

Some of the more than 350 protesters there vandalized businesses, set dumpster fires and hurled projectiles at officers, Police Chief Chris Magnus said. Three people were arrested for obstruction and one for aggravated assault on a police officer.

Magnus said he was hoping for a more peaceful protest Saturday. He also acknowledged that people were hurting and agreed that Floyd’s death after a Minneapolis police officer knelt on his neck should never have happened.

“It’s a very tough time for police, but an even tougher time to be a black person in this country,” Magnus said.

Phoenix Police Chief Jeri Williams said Phoenix was asking other law enforcement agencies for aid. Also, police would be more proactive in dispersing an unlawful assembly, she said.

“What we tolerated last night will not be tolerated today,” Williams said. “Officers will and must take action to protect the safety of all involved.”

Protests have erupted in U.S. cities in the days since Floyd’s death Monday.

The Rev. Jarrett Maupin, an organizer of the Thursday night protest, said tonight’s protest would be “more of a teach-in and a reach-out.”

Gov. Doug Ducey said in a statement that he and the state Department of Public Safety director respected protesters’ rights to assemble.

“We will not, however, tolerate rioting, looting, violence, destruction of property or any behavior that endangers the safety or rights of other individuals,” said Ducey, who made no mention of Floyd’s or Johnson’s deaths.

Johnson was shot during a struggle after a trooper found him passed out in his vehicle. Phoenix police are investigating.

Johnson’s mother, Erma, told the Arizona Republic that her son never would have engaged in a struggle with police, and she questioned the police account.

“It’s a lot of things that I want to know that happened to my son in the last minutes of his life,” she said.

Dion Johnson’s last name has been corrected in two references in this story.

Copyright 2020 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.