A fire destroyed a memorial to the unarmed 18-year-old black man killed by police officer Darren Wilson Tuesday, Efe reported citing KSDK television.
Police officers gathered on Ferguson's main street after receiving reports of shots fired in the area and protesters milled around the site of the worst clashes between law enforcement agents and demonstrators following Brown's death Aug 9.
At least one shop had been vandalised and the crowd numbered about 200 people by 9 p.m. "It is still not clear if the shots were connected with the act of vandalism," a police spokesman told the TV station.
Police officers gathered on Ferguson's main street after receiving reports
The owner of the vandalised shop said this was the third time his business had been attacked. Social-networks cited some witnesses who said they heard protesters chanting "Burn it down!"
As police officers moved in to disperse the protesters, employees of local shops boarded up the stores to protect windows.
Ferguson police chief Thomas Jackson said that firefighters were called to extinguish the fire at the Michael Brown memorial since his officers were unable to put it out.
Hours after the memorial burned, residents reconstructed it, and investigators have not determined what caused the fire.
The National Guard was deployed in Ferguson, a town of 21,000 north of St. Louis, to quell the riots that left scores arrested and wounded in clashes with police, but sporadic demonstrations have continued because police officer Darren Wilson has not been indicted.