At least 2,000 demonstrators attended the march to City Hall, the largest turnout since 25-year-old Freddie Gray died a week ago in a police van.

A group of around 100 protesters splintered from the main march and threw objects at police officers and their cruisers, authorities said. The windows of several businesses were smashed, Police Commissioner Anthony Batts said. Police arrested 12 people who ignored orders to disperse, Batts said. At least one officer was hurt in the violence that ensued.

Baltimore Mayor Rawlings-Blake, who has called for answers in Gray's death, said agitators at the Saturday demonstration disrupted the otherwise peaceful political action.

"I am profoundly disappointed to see the violence in our city this evening," she said.

Fredericka Gray, Freddie's twin sister, joined Rawlings-Blake at the news conference where she urged people to keep calm.

"Freddie's father and mother do not want violence - violence does not get justice," she said.

Investigation underway

Gray died on April 19 after suffering a spinal injury while in police custody.

With his death, Gray joined a long list of black men who have died under questionable circumstances during police encounters in recent months. The highly publicized incidents have triggered an outcry over the use of force by law enforcement against African-Americans.

Last year, weeks of protests followed the fatal shooting of unarmed black teen Michael Brown by a white officer in Ferguson, Missouri, and the chokehold death of Eric Garner in New York City.

Six Baltimore police officers have been suspended in the Gray case, and an internal police investigation is under way.

Much of the violence occurred near the Camden Yards ballpark, where the Baltimore Orioles played the Boston Red Sox as scheduled. Towards the end of the game, fans were told to stay in place because of safety concerns.

Protesters are calling for the prosecution of the six officers involved in Gray's arrest and a reform of policing tactics.

glb/jil (Reuters, AP)