Police in Ferguson, Missouri clashed briefly with protesters outside their headquarters Wednesday night.
At least four protesters were arrested.
The incident comes as the St. Louis suburb remains tense ahead of a grand jury decision about whether a white police officer will be charged in the fatal shooting of a black teenager.
Somewhere between 50 and 80 people had gathered outside the Ferguson police department Wednesday night to demand that Darren Wilson, a white police officer, be indicted for shooting and killing Michael Brown last August.
Decision in a few days
A grand jury decision on the matter is expected in a few days.
Even though protesters in relatively smaller numbers, sometimes as few as only one or two, have been demonstrating outside the police headquarters nonstop since the shooting, the situation has not escalated this far for over a month.
Police in riot gear moved in quickly Wednesday night, grabbed a couple of protesters, and moved back without breaking their formation - a move that was repeated several times.
Protesters had briefly blocked traffic and police had warned them with a bullhorn to clear the street before moving to arrest them.
The Ferguson police department refused to comment.
Rasheen Aldridge Jr., director of Young Activists United and the youngest member of the newly appointed Ferguson Commission, called the police tactics "unnecessary" and said the riot gear worn by police "doesn't make sense."
The situation in the area is tense. Many local shops have boarded up their fronts. Schools have announced plans for early closures or shutdown when the grand jury decision is announced.
Authorities fear violence
Some nearby municipalities have asked residents to stock up and plan as if a storm or natural disaster were coming. Authorities fear that if Wilson is not indicted, the protests could turn violent.
The governor of Missouri has declared a state of emergency and activated the National Guard to plan for any contingency.
Protesters insist authorities are creating mass hysteria when they should be calling for calm.
"If you look, you see peaceful protesters. What is the reason for the state of emergency? But if you look over here, police are in SWAT gear, I mean in riot gear, for no reason,” Aldridge said.
The protesters do admit, however, that "outside agitators" may try to turn peaceful protests violent.
Protests in the aftermath of Brown's death turned violent.