Angry civil rights groups on Sunday were pressing for new criminal charges following George Zimmerman's acquittal on second-degree murder and manslaughter in a Florida courtroom.
The NAACP website featured an online petition -- also posted on the liberal site MoveOn.org -- asking the Justice Department to bring federal charges against Zimmerman in the February 2012 fatal shooting of Trayvon Martin.
"The most fundamental of civil rights - the right to life - was violated the night George Zimmerman stalked and then took the life of Trayvon Martin," the petition says. "We ask that the Department of Justice file civil rights (criminal) charges against Mr. Zimmerman for this egregious violation."
Barbara Arnwine, executive director of the Lawyers' Committee for Civil Rights Under Law, issued a statement Sunday asking for federal civil rights charges and blasting the verdict as a "tragic miscarriage of justice." She also urged Trayvon's family to pursue a civil lawsuit.
"No matter how you look at this situation, if it were not for the actions of Mr. Zimmerman, Trayvon Martin would still be alive with his family today," Arnwine said.
She said she hoped the verdict would spark a national conversation about racial profiling and the "broken criminal justice system."
After the verdict was announced Saturday night, a clearly shaken NAACP President Benjamin Todd Jealous said, "This is a heartbreaking moment. This will confirm for many that the only problem with the New South is it occupies the same time and space as the old South."
He referenced another killing of a black youth that many have compared to the Trayvon Martin slaying, the 1955 killing of 14-year-old Emmett Till, who was killed in Mississippi for allegedly flirting with a white woman. "Trayvon Martin's case has focused a generation the same way that the Emmett Till case focused a generation 60 years ago. I had hoped that this time we would get a verdict that fit the gravity of the case."
The Rev. Al Sharpton, who led thousands of protesters in Sanford seeking a prosecution of Trayvon's killer, called the verdict "a sad day in the country" and "a slap in the face to those that believe in justice in this country."
"I think this is an atrocity," Sharpton said. "It is probably one of the worst situations that I have seen."
Jesse Jackson called the verdict "Old South justice."
"I'm disappointed and I'm saddened for the family," Jackson said.
While the jury's verdict was a crushing blow for many, there were no reports of serious unrest by early Sunday morning. Authorities in Martin's hometown of Miami and in Miami Gardens, where his father lives, said the streets were quiet.
Demonstrators took to the streets of four California cities, and there were reports of protesters breaking windows and damaging cars in Oakland, officials said early Sunday.
In Chicago, about 40 people chanted "Justice for Trayvon!" as they marched through the streets Saturday evening, according toThe Chicago Tribune.
In Sanford, Tristan Bailey, 15, who was outside the Seminole County courthouse, was stunned after hearing the verdict. "I don't know what to say," said the teen, who identifies with Trayvon Martin. "He was just a teen, trying to live his dreams."
Shannon Mickey, 41, was also disappointed. "We were all nervous when we knew the verdict was coming down," Mickey said. "It was a sense of shock. And unbelievable sadness."
In Detroit, the Rev. Charles Williams II, president of the National Action Network of Michigan and pastor of Detroit's Historic King Solomon Baptist Church, said he planned a special prayer service at the church to pray for the Martin family.
"In the South, it's still hard for an African American to get justice," Williams said. "Mr. Zimmerman deserved at least manslaughter and the jury wouldn't even do that. There is not faith in the jurors or in the diversity of the process."
Williams said that National Action Network will examine legal options. "We're going to continue our calls for justice for Trayvon Martin," he said.
In Fort Myers, Fla., people voiced feelings of anger, dismay and concern about keeping the peace immediately following the verdict.
"Oh my goodness, this is unreal to me. I'm very upset," said Antoinette Anderson, 48, a school district employee who is African American. "It shows we're not equal in the justice system."
Joe D'Alessandro, a 74-year-old former state attorney who now has a private legal practice, had a different take: "I never thought the state had a second-degree murder case," he said. "Self-defense trumps all. I just hope there's no violence."
Despite his disappointment with the verdict, Jealous urged calm. "It's important that the public focus on the fact that there are still additional avenues for holding this man accountable and bringing him to justice," he said. "It is critical that people keep the peace and focus their energy on encouraging the federal authorities to make sure that Zimmerman is held accountable for taking young Trayvon Martin's life."
Jackson also called for calm. "I hope there will be dignity and discipline, and not street justice," he said. "We cannot dishonor the innocent blood of Trayvon Martin with acts of violence."
Tampa resident Craig Woodord brought his 13-year-old son, Dante, to the courthouse Saturday afternoon to watch history in the making. Dante wore a blue hooded sweatshirt and carried a bag of Skittles candy and a can of watermelon Arizona Iced Tea.
"My son's 13," Craig Woodord said. "And it could have been him. So my heart really, really goes out to the Martin family, who lost their son that was doing absolutely nothing wrong.
"But nobody wins tonight. George Zimmerman is free, but he has to come out into society - living with a lot of people that don't like him."
Contributing: John Bacon; Mackenzie Ryan and Rick Neale of Florida Today; John Wisely, Detroit Free Press; Laura Ruane, The News-Press in Fort Myers, Fla.; The Associated Press