Philadelphia, Pennsylvania - More than a dozen people were arrested overnight in Philadelphia following looting of stores after a peaceful rally against police violence, officials said.

Business windows were smashed in, and shops were plundered by "large groups of juveniles" in the city center on Tuesday evening in a spate of violence that had "nothing to do" with the day's earlier demonstrations, Police Commissioner John Stanford said.

"What we had tonight was a bunch of criminal opportunists take advantage of a situation and make an attempt to destroy our city," Stanford told a press briefing.

Police made "somewhere around 15 to 20 arrests," he said, promising that they would make more.

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Some 30 minutes after protests had died down, police began receiving emergency phone calls around 8:00 PM concerning break-ins and pillaging at shops, including popular yoga gear brand Lululemon and shoe store Foot Locker.

Demonstrators had taken to the streets after a Philadelphia court earlier in the day dismissed murder charges against a police officer who fatally shot 27-year-old motorist Eddie Irizarry during a traffic stop last month, a violent incident that was captured in bodycam footage.

Controversy over the use of firearms by police in the US during contentious traffic stops is widespread, with officers routinely saying they have acted in self-defense to avoid charges.

The looting episode, which Stanford said was carried out by a crowd of up to "a hundred or so" individuals, comes as organized shoplifting and petty theft are on a rise in the United States.

In cities such as Los Angeles and Chicago, a recent trend in brazen raids by violent flash mobs has resulted in the theft of hundreds of thousands of dollars of luxury goods.