A march and prayer vigil that began as a way to honor Michael Brown, an unarmed black teenager who was killed by police Saturday, ended with looting and violence in suburban St. Louis Sunday night. At least one store was set on fire.The killing, and the protest against it, happened in Ferguson, Mo., where Brown, 18, was shot and killed during an altercation with a Ferguson police officer in a street lined with houses Saturday. Police and witnesses agree the teen did not have a gun and that a third person was also involved; beyond that, the details of Brown's death are in dispute.Protests against the officer's killing of Brown began shortly after the incident occurred in Ferguson, a predominately African-American community northwest of downtown St. Louis. On Saturday, Brown's stepfather, Louis Head, was seen holding a cardboard sign reading, "Ferguson police just executed my unarmed son."The case is being investigated by an outside agency, the St. Louis County Police Department.Before violence broke out late Sunday, protesters had been chanting "Hands up, don't shoot! Hands up, don't shoot!"St. Louis Public Radio's Rachel Lippmann describes the scene before things boiled over:"The crowd that gathered near the site of the shooting, in the Canfield Gardens apartment complex, was large but peaceful. Community leaders called for a boycott of Ferguson businesses, and collected money to pay for Michael Brown's funeral.""His nickname was Mike Mike, he was called a 'gentle giant' by many of the people who knew him" Lippmann says of Brown on today's Morning Edition. Those people also say of Brown, who was to have begun classes at a local college today, "fighting wouldn't have been in his nature — and the violence that erupted in his name wouldn't have been in his nature."That violence broke out after a series of peaceful and passionate rallies for Brown, Lippmann says. After a QuikTrip convenience store near the site of the shooting was overrun and set on fire, the looting quickly spreading to an area five miles wide.From the AP: