SANFORD, Fla. -

The parents of a 17-year-old boy killed in Sanford last month joined the Rev. Al Sharpton on Thursday afternoon to address a crowd in Sanford ahead of a rally to call for an arrest in the case.

Trayvon Martin died Feb. 26 after police said George Zimmerman, 28, shot him. Zimmerman claimed self-defense and was not arrested.

RAW VIDEO: Sharpton, Martin's parents speak

PHOTOS: Trayvon Martin protests

RELATED: S. Fla. students rally for Trayvon

Sharpton and Martin's parents, Tracy Martin and Sybrina Fulton, spoke to a crowd before the rally after the Sanford police chief announced he is temporarily stepping down.

"We did not come here for a temporary leave of absence. We came for permanent justice," Sharpton said. "Arrest Zimmerman now. That's what this rally is about. Investigate the entire police department from top to bottom. We don't need temporary relief. We need permanent change."

"I think, since the chief has stepped down, it's a temporary relief, but we need a permanent relief. I still say we need an arrest," said Fulton.

Benjamin Crump, the attorney for the Martin family, commented on the response from people in New York.

"The people of New York let Tracy and Sybrina know that the Trayvon Martin movement for justice is just not here in Florida. It is in New York City. It is in Los Angeles, Calif. It is in London, England. It's going to keep going until they arrest, prosecute and convict George Zimmerman," Crump said.

"We want you all to know that you are Trayvon," Tracy Martin said.

Martin's parents meet with DOJ officials

Martin's parents met Thursday with U.S. Justice Department officials, hours before thousands of protesters were expected for a rally led by Sharpton. Tracy Martin and Fulton met with Robert O'Neill, the U.S. attorney for the Middle District of Florida, and Roy L. Austin Jr., who is deputy assistant attorney general of the department's Civil Rights Division.

Tracy Martin and Fulton discussed the police investigation into the shooting death of their son. The State Attorney's Office is reviewing the case, which will be presented to a grand jury next month. However, the Justice Department earlier this week agreed to open a federal civil rights probe into the Feb. 26 shooting.

Tracy Martin and Fulton, believe Zimmerman should have been arrested. They claim Zimmerman was profiling their son and acted like a vigilante.

Sanford Police Department officials said there is no evidence that contradicts Zimmerman's claim of self-defense. Some neighbors in the gated community where Martin was shot have praised Zimmerman for taking a stand against crime in the neighborhood.

Florida's self-defense law gives people wide latitude to use deadly force rather than retreat during a fight.

The lack of an arrest has outraged residents who claim the Sanford Police Department has a history of ignoring the black community's concerns. City commissioners gave the police chief a vote of no confidence on Wednesday. The commission can't fire the chief because he reports to the city manager. The city manager said he will take the 3-2 vote under consideration.

Thousands of protesters were expected Thursday evening at an outdoor public park for a rally demanding that Zimmerman be charged. It had been scheduled to be held in a 400-seat church, but the rally was moved to accommodate the large number of protesters expected.

The rally is being headlined by Sharpton, who flew down to central Florida despite the death of his mother earlier in the day.

"My mom would have wanted me to," Sharpton wrote on Twitter.

Embattled police chief steps down

The police chief who has been bitterly criticized for not arresting a neighborhood watch volunteer in the shooting death of an unarmed black teenager announced Thursday that he is temporarily stepping down to let passions cool. 

Sanford Police Chief Bill Lee's decision came less than a day after city commissioners gave him a "no confidence" vote, and after a couple of weeks of protests and uproar on social media websites. Lee has said the evidence in the case supported George Zimmerman's claim that the Feb. 26 shooting of 17-year-old Trayvon Martin was self-defense.

"I do this in the hopes of restoring some semblance of calm to a city which has been in turmoil for several weeks," Lee said. 

Martin was returning from a trip to a convenience store when Zimmerman started following him, telling police dispatchers he looked suspicious. At some point, the two got into a fight and Zimmerman pulled out his gun. 

Zimmerman told police Martin attacked him after he had given up on chasing the teenager and was returning to his sport utility vehicle. 

The shooting ignited racial tensions in this Orlando suburb. Civil rights groups have held rallies in Florida and New York, saying the shooting was unjustified. 

The police chief continued Thursday to stand behind his agency's investigation. 

"As a former homicide investigator, a career law enforcement officer and a father, I am keenly aware of the emotions associated with this tragic death of a child. I'm also aware that my role as a leader of this agency has become a distraction from the investigation," Lee said. 

It wasn't immediately how long the police chief would step aside. 

The Justice Department and FBI have opened a civil rights investigation, and the local prosecutor has convened a grand jury April 10 to determine whether to charge Zimmerman. 

Some people believed Lee should step down for good. 

"If they wanted to defuse a potential powder keg, he needed to resign," said pastor Eugene Walton, 58, who was born and raised in Sanford. "His inaction speaks loudly to the black community." 

News of the police chief's decision to step aside spread quickly among the 1,000 protesters who had shown up more than two hours before the start of the rally Thursday. They chanted "The chief is gone. Zimmerman is next." 

Some carried signs that said: "100 years of lynching, justifiable homicide. Same thing." Others sold T-shirts that said: "Arrest Zimmerman." 

"It's the norm around here, where anything involving black culture, they want to wipe their hands of it," said Shella Moore, who is black and grew up in Sanford.