ST. PAUL, Minn. - Thousands of people gathered on the steps of the Minnesota State Capitol Friday night after Jeronimo Yanez was acquitted of all charges in connection with the shooting death of Philando Castile.

Protesters held signs, banners, sang and chanted in response to the not guilty verdict in the case of Yanez, a former St. Anthony Police officer, who shot and killed Philando Castile during a traffic stop in Falcon Heights last July.

After the hour-long rally, protesters took to the streets, marching west on University Avenue. Saint Paul Police escorted the crowd they estimated to be 2,000 people. The march, which appeared to be peaceful, later spilled onto Interstate 94 at Dale Street. About 500 or so protesters blocked the roadway. A line of police in riot gear eventually met them, and demonstrators were warned they will be arrested if they don't disperse. By 12:30 a.m. Saturday, police had largely cleared the demonstrators.

The Minnesota State Patrol arrested 18 people in conjunction with the shutdown.

After people moved from the highway a hundred or so moved to the Governor's mansion. The crowd had dispersed by about 3:30 a.m. Candles were left as a memorial to Philando Castile.

Earlier in the day, family, friends and supporters of Castile expressed both grief and outrage at the finding. The reading of the verdicts triggered a loud expletive from Valerie Castile, Philando's mother, and sobbing could be heard as the family made its way out of the courthouse. She later expressed more outrage on a profanity-laced Facebook Live video.

That grief, however, was soon pushed aside by burning anger, as Castile's mother stepped before a microphone and vented before reporters.

RELATED: Yanez found NOT GUILTY in Castile shooting

"I'm mad as hell right now, yes I am," shouted Castile. "My first born, No. 1 son, dead, here in Minnesota. Under the circumstances, just because he's a police officer, that makes it OK. Now, they got free reign."

"He shot into a car with no regard for human life," she continued, "and that's OK. Thank you, Minnesota."

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<p>Valerie Castile seethed with rage, lamenting what she calls the lack of justice for African American people in this country. </p>

Allysza Castile, Philando's younger sister, was more resigned while speaking to reporters.

"The system really is wrong, they really failed us," she said through tears. "They really failed us again, because my brother is a good man."

Judge Glenda Hatchett, who is representing the Castile family in likely civil actions against Jeronimo Yanez, insisted that the fight to protect African-American people like Philando Castile from violent police actions is not over, but admitted the verdict was a bitter pill to swallow.

"I said in July when I first stood before you that this case would mark a turning point in this nation. I'm disappointed it has not, I believe that this time we had to get it right, " Hatchett insisted. "This time we had a young man who had no criminal record ... we didn't have a man who was fleeing from the scene, we didn't have man fighting with the police, we had a man who was fully compliant as his mother taught him."

"If Philando can die under these circumstances, let's be clear -- each of you could die under these circumstances."

Castile's girlfriend, Diamond Reynolds, was with him in the car when Castile was fatally shot by Yanez. She did not appear on camera but released a statement to reporters reacting to the verdicts.

Family members weren't the only ones left struggling with the verdict, and a sense that justice was not served. The St. Paul Public Schools, Castile's employer for 13 years, tweeted a statement underlining that "Mr. Phil's" death has changed the community forever.