World Bulletin / News Desk 

At least 12 arrests were made Saturday during protests in Baltimore over the death of a black man while in police custody.

A video posted on social media showed one protester smashing a trash can against the window of a police car while other demonstrators attacked civilian cars. Some protesters were seen throwing water bottles and other objects at police.

About 1,000 demonstrators marched in the city while hundreds of police officers created a human barrier around protesters.

Police said a smaller group of demonstrators broke away from the core group of protesters and was largely responsible for the chaos as demonstrators called for justice for Freddie Gray, a 25-year-old black man who died from a severed spine a week after being arrested.

Protesters had promised to turn the Baltimore demonstrations into the biggest march in the country against police violence.

At a late day press conference, the city’s mayor said the violence and vandalism was “unacceptable” and Gray’s twin sister appealed for calm.

"My family wants to say, can you all please, please stop the violence? Freddie Gray would not want this," said Fredericka Gray.

Cell phone video of the arrest showed Gray with his hands behind his back, screaming as police lifted him to his feet and dragged him into a transport van.