BREAKING NEWS:FERGUSON GRAND JURY HAS REACHED THE DECISION IN MICHAEL BROWN SHOOTING

CLAYTON, Mo. — A St. Louis County grand jury has brought no criminal charges against Darren Wilson, a white police officer who fatally shot Michael Brown, an unarmed African-American teenager, more than three months ago in nearby Ferguson.

The decision was announced Monday night by the St. Louis County prosecutor, Robert P. McCulloch, at a news conference packed with reporters from around the world. The killing, on a residential street in Ferguson, set off weeks of civil unrest — and a national debate — fueled by protesters’ outrage over what they called a pattern of police brutality against young black men.

The St. Louis area was steeped in anxiety as it waited for the decision by the grand jury, which was made up of nine whites and three blacks and had been meeting on the case since Aug. 20. Mr. McCulloch said that Officer Wilson faced charges ranging from first-degree murder to involuntary manslaughter.

As darkness fell and word of the decision in the case spread, a growing, tense group of hundreds of protesters gathered outside Ferguson Police Headquarters as a line of police officers stood watch nearby. Many of protesters stood in the middle of the street, and all traffic was blocked. Some people wore masks. "Whose streets! Our streets!” some chanted. “We’ve got to fight back!”

Law enforcement authorities had been on alert in preparation for unrest if no indictment was returned. Even before the decision was announced, National Guard troops were dispatched to a police command post; political leaders, including Gov. Jay Nixon, flew here to hold last-minute meetings with community members; schools closed for the week; and businesses and residents, including parents of schoolchildren, braced for what might come next.