Adrien Schless-Meier, 24, joins protestors in front of the White House calling for the prosecution of the officer who shot unarmed black teenager Michael Brown in Ferguson, Mo. (Amanda Voisard/For the Washington Post)

About 20 people demonstrated silently outside the White House Saturday afternoon against what they called police brutality in the St. Louis suburb of Ferguson and called for the prosecution of the officer who shot an unarmed black teenager.

That shooting has sparked days of protests in Ferguson and led to flashes of violence rioting. It has also energized groups around the country to come out against what many have called excessive enforcement by some police officers.

The group that gathered Saturday walked in a circle carrying signs urging “justice and equality” and “stop police brutality now” and some taped their mouths shut with American-flag-patterned duct tape. They also called for legislation that would require officers to wear cameras.

The protest was organized by Autumn Colbert, 30, a licensed Maryland social worker who described herself as a “concerned citizen” over the shooting of Michael Brown. The demonstration was not affiliated with any official group.

“I was completely shocked and stunned even though it’s happened before,” Colbert said of the shooting of an unarmed black man. “I had to start organizing.”

Autumn Colbert, 30, marches in front of the White House on Aug. 16. (Amanda Voisard/For the Washington Post)

Colbert started posting on Facebook, Twitter and Instagram about the protest, where most said they had heard about the event. Colbert added that she wanted to protest in front of the White House “because we need to bring it to the national stage.”

Among the protestors was Porsha Doyle, 27, who carried a poster with a photo of her 1-year-old nephew Christopher and the words “Will he live to go to college?”

“The people of Ferguson deserve a voice,” said Doyle, who grew up in St. Louis. She recalled walking to a friend’s house when she was 19 and being stopped by cops who searched her car after misinterpreting her move to get something in her purse.

“People aren’t just mad for no reason,” she added.

Some of the protestors said they wanted a stronger national response to the Ferguson shooting.

“This shows systemic problems in police forces across the country,” said Adrien Schless-Meier, 24. She cited President Obama’s and Attorney General Eric Holder’s speeches mentioning concern over looting before discussing the police’s actions as a source of frustration.

“Looting is such a loaded term,” Schless-Meier said, adding it “perpetuates the idea that black people are criminals.”

But Alexandria resident Victoria Comsa, 60, described the president’s response as “okay.”

“I’m glad he got Eric Holder involved immediately,” she said, as she held a sign over her Obama 2008 shirt.

After the protest, the demonstrators walked to 17th Street and Pennsylvania Avenue, where they introduced themselves to each other and shared hugs. Colbert encouraged them to take the signs home with them.

“That was a beautiful show of humanity,” she said.