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Terrified neighbors implored dispatchers to send police as a voice in the background screamed for help in 911 recordings released after the shooting of an unarmed Florida teen.

Trayvon Martin, 17, was returning from the store to the Sanford home of his father's fiancee when he has shot last month.

Authorities released seven 911 calls Friday, all of which describe hearing a gunshot.

The teen's parents broke down when they heard the recordings detailing the last moments of his life, said their attorney, Benjamin Crump.

"They are completely devastated, and they are in unbelievable grief," Crump told CNN affiliate WKMG.

Martin was carrying a drink and candy when George Zimmerman, a neighborhood watch captain, called 911 to report a suspicious man, authorities said.

The 911 dispatcher told Zimmerman not to confront him. But by the time police arrived, Martin lay dead with a gunshot wound in the chest, according to Sanford Police Chief Bill Lee.

911 tapes released Friday detail moments of terror in the neighborhood as residents made a flurry of calls describing a gunshot and a teen wailing for help.

In some of the recordings, a voice screams "Help, help!" in the background.

"There were gunshots right outside my house. There's someone screaming, I just heard a guy shot," a neighbor says. "Hurry up, they are right outside my house."

Recordings mirrored the same details: A man outside was crying for help, followed by the sound of a gunshot.

"Hurry please ... there's someone screaming outside," a neighbor whispers. "There's a gunshot, hurry up ... there's someone screaming. I just heard a gunshot."

In another call, a woman begs the dispatchers to send help, saying someone is "screaming and hollering" for help.

Moments later, she describes a light at the scene of the shooting.

"Oh my God ..." she said, "There's still somebody out there walking with a flashlight."

Zimmerman told police he shot the teen in self defense, authorities said, and remains free as the state attorney investigates. Police said he has not been charged because there are no grounds to disprove his story of what happened.

"The evidence and testimony we have so far does not establish that Mr. Zimmerman did not act in self-defense," the police chief said. "We don't have anything to dispute his claim of self-defense, at this point, with the evidence and testimony that we have."

Police released the tapes the same day the teen's relatives said the they are outraged that Zimmerman remains free.

"It's surprising. It's shocking," said Tracy Martin, the victim's father. "It lets me know that justice is just not being served here. All we want is justice for our son. We're not asking for anything out of the ordinary."

CNN has made numerous attempts to contact Zimmerman, but have been unsuccessful. It is unclear whether he has retained an attorney.

Some have accused Zimmerman, who is Hispanic, of profiling the black teen.

His father delivered a statement to the Orlando Sentinel this week saying his son moved out of his home after receiving death threats. George Zimmerman is Hispanic and grew up in a multiracial family, the statement says.

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