Story highlights The mothers of Trayvon Martin, Michael Brown, Tamir Rice and Eric Garner meet

Martin's mother: All four victims were unarmed and African-American

If Garner were white, he would be alive today, his mother says

The mothers of these four unarmed black men and boys felled by bullets or excessive police force have no doubt their sons would still be alive if they were white. No question, they say.

"I think absolutely my son's race and the color of his skin had a lot to do with why he was shot and killed," Sybrina Fulton, Martin's mother, told CNN's Anderson Cooper on Friday. "In all of these cases, these victims were unarmed. These victims were African-American. That needs to be our conversation."

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In their first interview together, Fulton was joined by Brown's mother, Lesley McSpadden; Tamir's mother, Samaria Rice; and Garner's mother, Gwen Carr. They spoke of reliving the horrific final moments of their son's lives with each controversial death, of gaining strength from protesters and other supporters, of the importance of coming together to effect change.

"It seems our kids are getting younger and younger," Fulton said. "They're killing them younger and younger. There is no regard anymore for human life. There has to be somewhere where we draw the line and say, 'Listen, our kids want to grow up, too.'"

Carr said she had confidence in a federal investigation into whether her son's civil rights were violated. A Staten Island grand jury last week refused to indict a white police officer in the death of her son, was put in a fatal chokehold by the officer as he tried to arrest Garner for illegally selling cigarettes.

"If Eric Garner was a white man in Suffolk County doing the same thing that he was doing -- even if he would have been caught selling cigarettes that day -- they would have given him a summons and he wouldn't have lost his life that day," she said. "I believe that 100 percent."

Fulton's son was shot and killed in Florida in February 2012 by George Zimmerman, a volunteer neighborhood watch captain. The case quickly drew national attention as weeks went by without formal charges.

"We have to change mindsets," Fulton said. "We have to let people know that our children matter. Our sons and our daughters matter. We are hurting. This country is hurting."

Demonstrations followed Zimmerman's acquittal even though some people around the country supported Zimmerman's actions.

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"It's not happening to them, so they don't quite get it," she said. "They don't quite understand. They think that it's a small group of African-Americans that's complaining. ...The people say that all the time: 'What are they complaining about now? What are they protesting about now?'"

To those people, Fulton said: "Until it happens to them and in their family then they'll understand the walk. They don't understand what we're going through. They don't understand the life and they don't understand what we're fighting against. I don't even think the government quite gets it."

President Barack Obama publicly addressed the Martin case, as he did last summer's shooting of Brown -- an unarmed teenager shot to death by white police Officer Darren Wilson. A St. Louis County grand jury declined to bring charges against the officer, leading to days of unrest in Ferguson, Missouri.

"I was (sure) they would indict the officer that shot my son without a video tape," McSpadden said. "You had so many witnesses."

The death of Rice, a 12-year-old boy shot last month by a Cleveland officer after police allegedly mistook the child's air gun for a real firearm, has also drawn national attention. The Cuyahoga County Medical Examiner's Office said Friday it has ruled the death a homicide.

Samaria Rice, his mother, said she found out about the shooting after two boys knocked on her door. "The police shot your son in the stomach," she recalled one of the boys saying.

One of her daughters was handcuffed and thrown into the back of a police car when she protested the shooting, said Samaria Rice.

She described going out to the street and seeing her son on the ground and "nobody ... doing anything" to help him. One of the Tamir's sisters screamed, "They killed my baby brother!"

Attorney Benjamin Crump, who has represented some of the mothers, said police cared more about preserving the crime scene than trying to save Tamir's life.

Fulton said each new tragedy brings people together.

"I think this is shedding light to what's going on," Fulton said of the protest movement that has risen out of the tragedies."This is not something new. It's been happening. ... But it's just been bringing light to what's happening. It's bringing it to the forefront which is why there's so much conversations. ... Because people are now realizing ... it's not just about African-American rights ... it's about human rights."

Carr asked, "What are they doing to our children today?"

Fulton said she has a son graduating from college next week.

"I want him to enjoy life and fulfill his life and goals, but at the same time I'm afraid for him," she said.