Darren Wilson, the Ferguson, Mo., white police officer, will not face charges for fatally shooting unarmed black teenager Michael Brown in a case that has set off weeks of violent protests and racial unrest throughout the nation, an attorney close to the case said Monday night, with prosecutors confirming the verdict at a news conference later on.

A St. Louis County grand jury has declined to indict Wilson for firing six shots, finding that no probable cause existed, said Benjamin Crump, an attorney for the family. The 28-year-old cop has been granted paid administrative leave to following weeks of violent protests that rocked the Ferguson community.

"They determined that no probable cause exists to file any charge against Officer Wilson," St. Louis County Prosecutor Bob McCulloch told reporters in Clayton, Mo., a suburb of St. Louis where the grand jury met.

Brown's family said they were "profoundly disappointed" by the grand jury's finding, The New York Times reported. "While we understand that many others share our pain, we ask that you channel your frustration in ways that will make a positive change," the family said in a statement released by its attorneys.

Before the decision was announced, Missouri Gov. Jay Nixon had urged that "regardless of the decision, people on all sides show tolerance, mutual respect and restraint.'' Previously, the Democrat had also declared a state of emergency and authorized the state's National Guard to support police in case of violence.

Large crowds had gathered around the Ferguson police headquarters in anticipation of the announcement at the courthouse in Clayton. The shooting has inflamed tensions in a largely minority community that is patrolled by an overwhelmingly white police force.

For three months, the 12-person grand jury, with nine white and three black members, had been considering whether probable cause existed to bring charges against Wilson, according to Reuters.

After an Aug. 9 confrontation between the 18-year-old and Wilson, Brown's lifeless and bleeding body lay for more than four hours in a Ferguson residential street, immediately igniting dismay and anger among the Ferguson community. On the following night, protests turned into rioting and looting, with police responding with armored vehicles and tear gas, triggering a nationwide debate over police tactics.

Brown's family joined thousands of protesters to demand Wilson's arrest. As anger at official inaction grew following Brown's death, protesters clashed with police, who began patrolling the streets with military-grade weapons and armored vehicles.

Based on media accounts, two starkly different versions of the events leading to the shooting have emerged.

"Police have said a scuffle broke out after Wilson asked Brown and a friend to move out of the street. Wilson told investigators he shot Brown only after the teenager reached for the officer's gun," according to USA Today. But according to some witnesses, "Brown had run away from Wilson, then turned and raised his hands in the air in a gesture of surrender before he was shot in the head and chest."

In another version, police have said Brown struggled with Wilson inside his police car, and then reached for Wilson's weapon, leading to gunshots being fired.

Although the unusual timing of the grand jury's announcement, after darkness had fallen, came into question, Nixon said it had been a decision of the prosecutors.

Since the decision was expected to potentially trigger further civil unrest in the Ferguson community, dozens of clergy members had already prepared to offer their churches as safe spaces, or sanctuaries, for people to escape the violent demonstrations, the Rev. Teresa Danieley, pastor of St. John's Tower Grove, said early Monday.

Organizations such as the Don't Shoot Coalition, which was formed after the death of Brown, and Metropolitan Congregations United, a group of interdenominational, multiracial congregations from around the region, are in the process of creating a list of churches that are volunteering the use of their space, according to Religious News Service.

Many of these churches, which will be packed with supplies such as food, water and phone chargers, will also have medics, legal observers and counselors on hand to function as police-free zones during protests.

"This is not the time to turn on each other; it is a time to turn to each other,'' said St. Louis County Executive Charley Dooley. "We are one community."

St. Louis Mayor Francis Slay acknowledged the case "has deeply divided us'' but said "turning violent or damaging property will not be tolerated.''

"The world will be watching us,'' Slay added.

Brown's family called for four and a half minutes of silence after the grand jury announcement, Maggie Crane, spokeswoman for Slay, said in a tweet Monday afternoon.

Meanwhile, Wilson could also face civil rights charges brought by the Justice Department or a civil wrongful death lawsuit filed by Brown's parents, the New York Daily News reported.