LOS ANGELES, July 16 (Xinhua) -- More than a dozen people were arrested overnight in Los Angeles area after a protest against George Zimmerman's acquittal turned violent, police said Tuesday.

Los Angeles Police Department (LAPD) said the rally started peacefully but later a group of young protestors broke windows, set fires and attacked several people. Some of them stormed a Wal-Mart store in Crenshaw, throwing merchandise to the floor.

Police arrested at least a dozen of protestors after failing to disperse them.

Mayor Eric Garcetti told a late-night press conference that a small group of protestors "has taken advantage of the situation."

It was the second day of protests in the Los Angeles area against Zimmerman's acquittal, with 100 to 300 protestors showed up each time.

Zimmerman, a 28-year-old neighborhood watch volunteer in Florida, was charged with a second degree murder after shooting dead 17-year-old African-American boy Trayvon Martin in February 2012.

A jury in Florida acquitted him Saturday, which triggered heated nationwide debate over potential injustice against ethnic minorities in the case and ensuing protests in some big cities, including New York and Oakland.