Protests have a way of getting very out of hand, very quickly. The officers of the St. Paul Police Department in Minnesota got a first hand look at how fast things can go south.

During a Black Lives Matter protest, hundreds of protestors blocked off Interstate 94 on Saturday night. What unfolded resulted in a clash between protestors and police, with police walking away with injuries due to protestors throwing rocks, rebar, fireworks, glass bottles, and more at police.

The St. Paul PD Twitter account described what happened in real time.

Traffic alert: I-94 East and Westbound in St. Paul is currently closed due to people marching on the roadway.

— St. Paul Police PIO (@sppdPIO) July 10, 2016

SPPD negotiating with protesters on I-94 to make symbolic arrests. Protesters in process of choosing those who will be arrested. #I94closed

— St. Paul Police PIO (@sppdPIO) July 10, 2016

As you can see, the protest began rather peacefully with police offering the protestors media exposure with symbolic arrests. However, protestors continued to block traffic on the Interstate.

SPPD has given 16 dispersal orders. Protesters still not leaving the freeway, continue to create safety hazard. #I94closed

— St. Paul Police PIO (@sppdPIO) July 10, 2016

Protesters just told–again–that they are participating in an unlawful assembly and that they can leave either north or south. #I94closed

— St. Paul Police PIO (@sppdPIO) July 10, 2016

At this point, the protestors began to get rowdy.

Protesters throwing objects at officers. #I94closed

— St. Paul Police PIO (@sppdPIO) July 10, 2016

Person with laser sight pointing it at officers. Fireworks being fired at officers by protesters. #I94closed

— St. Paul Police PIO (@sppdPIO) July 10, 2016

And it only continued to get worse.

Officer injured by fireworks thrown by protesters. #I94closed

— St. Paul Police PIO (@sppdPIO) July 10, 2016

Protesters now arming themselves with rebar from construction site. #I94closed

— St. Paul Police PIO (@sppdPIO) July 10, 2016

Protesters on overpasses throwing objects at officers, dumping liquid on officers. #I94closed

— St. Paul Police PIO (@sppdPIO) July 10, 2016

Officer injured after being hit with a glass bottle thrown by protesters. #I94closed

— St. Paul Police PIO (@sppdPIO) July 10, 2016

Officers attempted to mark the aggressors who were injuring officers.

Officers using marking rounds on aggressors. Aggressors still throwing rocks and bottles at officers. #I94closed

— St. Paul Police PIO (@sppdPIO) July 10, 2016

Aggressors now throwing rebar from construction zone at officers. Rocks continue to fly at officers. #I94closed

— St. Paul Police PIO (@sppdPIO) July 10, 2016

More fireworks being thrown at officers by aggressors. #I94closed

— St. Paul Police PIO (@sppdPIO) July 10, 2016

Despite their best efforts, officers were being hurt.

Another officer has been injured by aggressors throwing objects. Three injured so far. #I94closed

— St. Paul Police PIO (@sppdPIO) July 10, 2016

At this point, officers became concerned about the children involved in the protest, and worked to get them away from it.

Officers looking for children among protesters on I-94, trying to get them off the freeway. #I94closed

— St. Paul Police PIO (@sppdPIO) July 10, 2016

A truck with children in it has been removed from the freeway. #I94closed

— St. Paul Police PIO (@sppdPIO) July 10, 2016

After managing to send the children away, officers continued having rocks, bottles, and rebar thrown at them, and the injuries continued to climb despite officers making arrests.

Bricks now being thrown at officers, along with more rocks and bottles. #I94closed

— St. Paul Police PIO (@sppdPIO) July 10, 2016

An officer has been hit in the head with a rock. Unclear the extent of injuries. #I94closed

— St. Paul Police PIO (@sppdPIO) July 10, 2016

And things only escalated.

Another officer hit in the head with a large piece of concrete, possibly dropped from bridge. #I94closed

— St. Paul Police PIO (@sppdPIO) July 10, 2016

Molotov cocktail thrown at officers. Unclear if anyone injured. #I94closed

— St. Paul Police PIO (@sppdPIO) July 10, 2016

An officer was just hit in face with bottle thrown by a protester on St. Paul street. #I94closed

— St. Paul Police PIO (@sppdPIO) July 10, 2016

After the dust settled, St Paul PD took stock of the night.

Officers arrested 52 people for public nuisance and unlawful assembly during an incident at 4 this morning on Grand and Dale. #I94closed

— St. Paul Police PIO (@sppdPIO) July 10, 2016

Last night and this morning, 21 officers from multiple agencies were injured on I-94 and other areas of the city. #I94closed

— St. Paul Police PIO (@sppdPIO) July 10, 2016

One officers in particular suffered a very serious injury.

We were just informed that the officer who had a concrete block dropped on his head during I-94 riot has broken vertebrae.

— St. Paul Police PIO (@sppdPIO) July 10, 2016

According to Black Lives Matter leader, Lena Gardner, this protest had no intention of turning violent, and that the aggressors were outside agitators. 

“Black Lives Matter in Minneapolis has been and always will be committed to nonviolent protest,” said Gardner. “We’ve taken that position from the get-go and we have never wavered from it. And we don’t know.” 

Despite this protest’s intention to be peaceful, Mayor Chris Coleman described the protest as a riot. 

“Up to the point where people were peaceful – up to the point where they were sitting on the freeway, they may have been unlawfully assembling, but they weren’t rioting,” said Coleman. “The minute that brick was thrown, the minute the fireworks were thrown towards the police officer, that’s a riot.”

Let’s hope the officer injured makes a speedy recovery, and the tensions in St. Paul simmer down so that this kind of thing doesn’t happen again.