US President Barack Obama on Tuesday appealed for calm after what he called the "heartbreaking" death of a black teenager killed in a police shooting in Missouri that sparked rioting.
Looters targeted more than a dozen businesses in the St. Louis suburb of Ferguson overnight Sunday after a vigil on the sidewalk where Michael Brown died erupted into clashes with police armed with tear gas, clubs and rubber bullets.
Witnesses and police have given conflicting versions of how the 18-year-old was shot in broad daylight on Saturday, two days before he was due to start college.
"The death of Michael Brown is heartbreaking, and Michelle and I send our deepest condolences to his family and his community at this very difficult time," Obama said in a statement, his first public reaction to the incident, which has stirred racial tensions.
"I know the events of the past few days have prompted strong passions, but as details unfold, I urge everyone in Ferguson, Missouri, and across the country, to remember this young man through reflection and understanding," Obama added.
"We should comfort each other and talk with one another in a way that heals, not in a way that wounds. Along with our prayers, that's what Michael and his family, and our broader American community, deserve."
The FBI opened a civil rights investigation on Monday into Brown's death, with his family demanding justice.
Brown's death stirred comparisons to the February 2012 fatal shooting of unarmed teenager Trayvon Martin in Florida by pistol-toting neighborhood watch volunteer George Zimmerman, who claimed he acted in self-defense. He went on to be acquitted of murder, two years ago this week.
It also renewed a debate about race and law enforcement in the United States, a month after the death of an asthmatic African-American father of five who was subjected to a "choke hold" by New York police in full view of passers-by.