ST. PAUL -- Police in St. Paul, Minnesota, are confronting protesters who have blocked a downtown freeway following an officer's acquittal in the death of a black motorist.

Protesters have been demonstrating for hours with a rally that began Friday evening at the Capitol following the acquittal of Officer Jeronimo Yanez. He was charged with manslaughter in the death last July of Philando Castile.

Hours after the mostly peaceful demonstration began, a splinter group of scores of protesters walked down a ramp onto Interstate 94. A line of police in riot gear eventually met them, and demonstrators were warned they will be arrested if they don't disperse.

That rally gathered an estimated 2,000 people at the State Capitol Friday evening, CBS Minnesota reports.

Get Breaking News Delivered to Your Inbox

Three groups – Justice Occupation for Philando, Twin Cities Coalition for Justice 4 Jamar and Communities United Against Police Brutality – announced on Facebook earlier in the week they would hold a rally at the State Capitol the day the verdict was read.

After about an hour at the rally, the crowd headed toward I-94, shutting down several streets on the way. At around 10:50 p.m., the group started marching east on the interstate toward police.

The State Patrol estimated the group on the highway at about 500 people. They say they gave them an order to disperse soon after they arrived at the scene.