They run the gamut from a relative of a Colorado man killed by police last summer to a staffer at well-known St. Paul-based political action group, to the son of a state legislator and a folk singer.

All told, more than 100 people were arrested at protests over the weekend — some during what authorities called a riot on Interstate 94. Forty-six people were charged Monday with third-degree riot for the I-94 protest.

Police say they arrested others on Grand Avenue who they believed were on their way to block another interstate.

After a long series of mostly peaceful protests for racial justice in recent months, the situation got ugly on Saturday when some people took to hurling fireworks and rocks at police.

So, what went wrong, and who did it?

Black Lives Matter leaders and some witnesses on the scene say the violence started with just a few people who don't represent the movement. Police are still investigating and say 21 officers were hurt.

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Darryl Spence, a founding member of the God Squad, a group of pastors that serve as intermediaries in and for St. Paul's black community, was there. He said St. Paul Police Chief Todd Axtell called him Saturday night and asked for help.

"So I got about five or six of us, and we went, met up with the Department of Justice, and we stood between the police and the — I don't even know what to call it. The protesters," Spence said.

Police used smoke on protesters to try to clear the area during the shutdown of I-94 on Saturday. Christopher Juhn for MPR News

He'd been down earlier to meet with Black Lives Matter leaders, but not this time.

"I did not see the normal Black Lives Matter people. I saw people with masks on. They were ready for combat," Spence said. "They had gas masks, real gas masks. I was in the Air Force. I know what a gas mask. I was like, 'Where did they get this stuff from?'"

And then, he said, the trouble started.

"A white guy had a pallet in his hand. He was going to get ready to throw a pallet into the ranks of the police and they looked dead in my face and they said, 'You don't understand Black Lives Matter," and I said, 'What?'"

Spence said one of his friends took away the pallet, and they decided it was time to go. A brick hit Spence in the leg as he turned to walk back home, a few blocks away.

Rachael Hartzler of St. Paul was also there and told a similar story. She said the trouble seemed to start as someone dropped fireworks from a footbridge over the freeway about 9 p.m. She said Black Lives Matter organizer Adja Guildersleve called for them to stop.

"She yelled at the person above, and said you need to show discipline and focus," Hartzler said. "This is a peaceful protest and this had been repeated to us throughout the protest. They had been coaching people all along. This was peaceful, no violence will be tolerated."

Law enforcement form a line across Interstate 94 on Saturday in response to protesters who blocked the highway. Joe Danborn | AP

Black Lives Matter organizer Lena Gardner said she and her colleagues wondered if the disruption was deliberate.

"We understand this as a moment, that the movement is under attack. We understand that very clearly," Gardner said. "People from all corners are trying to de-legitimize us by coming to our protests and sabotaging them through violence."

Activists have even accused police themselves of infiltrating previous demonstrations to discredit Black Lives Matter and other critics of law enforcement.

St. Paul Police chief Todd Axtell called that assertion ridiculous and said his department's top priority is safety — both of the public and its officers.

Protesters watch police clean up I-94 after the police cleared people off the road. Christopher Juhn for MPR News

He says he too would like to know who is responsible for Saturday's violence.

"This investigation is active and it continues. And we are combing through any video footage we can find to look for those who were throwing rocks at our officers, throwing Molotov cocktails, throwing concrete, rebar, fireworks and other items that injured our officers," Axtell said.

But the police chief also said he isn't excusing people who thought they were doing nothing but inconveniencing motorists by blocking the freeway Saturday night.

"When police officers come under attack, and we continue to give orders to get away, it's a dangerous situation," Axtell said, "and they continue to sit there, I can't even put it into words how disappointing that is."

MPR News reporter Elizabeth Dunbar contributed to this report.