Looting and clashes with police broke a relative peace in Ferguson, Mo., late Friday night and early Saturday, but Missouri lawmakers called for the actions of a few not to tarnish the protest movement. 

Tensions between the police and demonstrators, sparked by the fatal shooting of an unarmed African-American teenager, Michael Brown, renewed as about 200 protesters threw rocks and other objects at police, according to the Associated Press. Others looted the convenience store police say Brown robbed before the shooting.

But there were also reports of residents guarding stores from looting. Rep. Lacy Clay (D-Mo.), whose district includes Ferguson, praised them.

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Earlier Friday, police named the officer who shot and killed Brown as Darren Wilson. Ferguson Police Chief Thomas Jackson said at a press conference that the six-year officer did not know Brown was a suspect in a robbery that took place minutes earlier.  

"The initial contact between the officer and Mr. Brown was not related to the robbery," Jackson said.

The robbery "had nothing to do with the stop," he added. 

The Washington Post reports that at other times, Chief Jackson appeared to contradict himself, and did say the robbery was a factor.

Police also released a surveillance video Friday of the alleged robbery. The focus on Brown's actions before the encounter where he was shot drew the condemnation of Clay.

"They have attempted to taint the investigation," the congressman told protesters through a bullhorn, according to the AP. "They are trying to influence a jury pool by the stunt they pulled today."

The Justice Department said the FBI had conducted interviews with witnesses as part of its investigation into Brown's death.

This post was updated at 10:23 p.m.