SANFORD, Fla. -

Neighborhood watch volunteer George Zimmerman was cleared of all charges Saturday in the shooting of Trayvon Martin, the unarmed black teenager whose killing unleashed furious debate across the U.S. over racial profiling, self-defense and equal justice.

Zimmerman, 29, blinked and barely smiled when the verdict was announced. He could have been convicted of second-degree murder or manslaughter. But the jury of six women, all but one of them white, reached a verdict of not guilty after deliberating well into the night. Their names have not been made public, and they declined to speak to the media.

Special section: George Zimmerman trial

Martin's mother and father were not in the courtroom when the verdict was read; supporters of his family who had gathered outside yelled "No! No!" upon learning of the not guilty verdict.

The teen's father, Tracy, reacted on Twitter: "Even though I am broken hearted my faith is unshattered I WILL ALWAYS LOVE MY BABY TRAY."

His mother also said on Twitter that she appreciated the prayers from supporters.

"Lord during my darkest hour I lean on you. You are all that I have," she wrote.

The jurors considered nearly three weeks of often wildly conflicting testimony over who was the aggressor on the rainy night the 17-year-old was shot while walking through the gated townhouse community where he was staying.

Defense attorneys said the case was classic self-defense, claiming Martin knocked Zimmerman down and was slamming the older man's head against the concrete sidewalk when Zimmerman fired his gun.

"We're ecstatic with the results," defense attorney Mark O'Mara after the verdict. "George Zimmerman was never guilty of anything except protecting himself in self-defense."

Another member of his defense team, Don West, said he was pleased the jury "kept this tragedy from becoming a travesty."

Prosecutors called Zimmerman a liar and portrayed him was a "wannabe cop" vigilante who had grown frustrated by break-ins in his neighborhood committed primarily by young black men. Zimmerman assumed Martin was up to no good and took the law into his own hands, prosecutors said.

State Attorney Angela Corey said after the verdict that she believed second-degree murder was the appropriate charge because Zimmerman's mindset "fit the bill of second-degree murder."

"We charged what we believed we could prove," Corey said.

As the verdict drew near, police and city leaders in the Orlando suburb of Sanford and other parts of Florida said they were taking precautions against the possibility of mass protests or unrest in the event of an acquittal.

"There is no party in this case who wants to see any violence," Seminole County Sheriff Don Eslinger said immediately after jurors began deliberating. "We have an expectation upon this announcement that our community will continue to act peacefully."

O'Mara, Zimmerman's attorney, said his client is aware he has to be cautious and protective of his safety.

"There still is a fringe element that wants revenge," O'Mara said. "They won't listen to a verdict of not guilty."

The verdict came a year and a half after civil rights protesters angrily demanded Zimmerman be prosecuted. That anger appeared to return Saturday night outside the courthouse, at least for some who had been following the case.

Rosie Barron, 50, and Andrew Perkins, 55, both black residents of Sanford, stood in the parking lot of the courthouse and wept.

"I at least thought he was going to get something, something," Barron said.

Added her brother: "How the hell did they find him not guilty?"

Perkins was so upset he was shaking. "He killed somebody and got away with murder," Perkins shouted, looking in the direction of the courthouse. "He ain't getting no probation or nothing."

Several Zimmerman supporters also were outside the courthouse, including a brother and sister quietly rejoicing that Zimmerman was acquitted. Both thought the jury made the right decision in finding Zimmerman not guilty — they felt that Zimmerman killed Martin in self-defense.

Cindy Lenzen, 50, of Casslebury, and her brother, 52-year-old Chris Bay, stood watching the protesters chant slogans such as, "the whole system's guilty."