PHOTOS: Protests Over George Floyd's Death Grow Violent: 'It Is How We Express Pain'

Outrage, frustration and grief are driving hundreds of protesters into the streets of Minneapolis, St. Paul and Los Angeles after the death of George Floyd, an unarmed black man who died at the hands of white police officer on Monday.

Over the last few days demonstrations in Minnesota have evolved from peaceful cries for justice into violence and destruction.

Floyd's arrest and final minutes of his life were captured in multiple videos that are circulating widely on social minutes. In all versions, Floyd is pinned to the ground with his hands handcuffed behind his back. The knee of white officer is crushing his neck, as another officer stands a few feet away. He is watching, seeming unfazed as the 46-year-old cries, "I can't breathe."

Angry crowds have looted businesses and burned buildings to ashes. Meanwhile, law enforcement has met the civil disorder with clouds of tear gas.

The unrest prompted Minnesota Gov. Tim Walz to activate the National Guard on Thursday to bring calm to the streets.

"It is how we express pain, process tragedy, and create change," he said about the act of protesting.

But he noted the urgency in responding to local leaders' call for the National Guard "to protect peaceful demonstrators, neighbors, and small businesses in Minnesota."

"It is time to rebuild. Rebuild the city, rebuild our justice system, and rebuild the relationship between law enforcement and those they're charged to protect," Walz added.

Lt. Gov. Peggy Flanagan added that the purpose of the National Guard is to ensure safe demonstrations and to protect small business owners.

"The anger and grief of this moment is unbearable. People deserve to be seen. People deserve to be heard. People deserve to be safe," Flanagan said.

"While many Minnesotans are taking extensive safety precautions while exercising their right to protest, the demonstration last night became incredibly unsafe for all involved," she added.

In all, four officers were involved in Floyd's death. All have been fired from the Minneapolis Police Department.

Several investigations into their actions have been launched, but as of Thursday, no charges have been filed.

Copyright 2020 NPR. To see more, visit https://www.npr.org.