Reaction to two grand juries' declining to indict white police officers in the deaths of two black men in Missouri and New York have kicked off "two of the worst weeks in American history in recent times," Mayor Nutter said Sunday on Meet the Press.

Appearing on the NBC morning news program with Philadelphia Police Commissioner Charles H. Ramsey, Nutter referenced civil unrest nationwide since the deaths of Michael Brown in Ferguson, Mo., and Eric Garner in Staten Island, N.Y., both African Americans, at the hands of white police officers.

Nutter indicated changes must be made to allow the public to trust the police after an officer shot Brown, and Garner died in an officer's chokehold.

He added that a "large gap" was growing in America: "Citizens . . . are now increasingly afraid of the police, and . . . some police officers . . . are increasingly afraid of the community."

Establishing trust in police is paramount, said Ramsey, whom President Obama appointed last week to cochair the Task Force on 21st Century Policing, which aims to provide recommendations for local departments on building trust within communities, especially those of color.

"It's troubling people do not believe there's fairness" in the way police and prosecutors interact with citizens, Ramsey said.

He added that police departments needed to "take a look at . . . training," that officers needed an enhanced education "so they better understand the role of police in a democratic society."

Camden County Police Chief Scott Thomson appeared on CBS's Face the Nation, discussing what his department has done to turn the tide of crime. Host Bob Schieffer said Camden "was ranked as the most dangerous city of its size just months ago."

"In less than 24 months," Thomson said, "we have begun a remarkable transformation of taking streets that were once controlled by criminals and drug dealers now being occupied by children riding their bicycles and families enjoying the front steps."

Thomson took over the countywide force established in May 2013 after the city's police department was disbanded.

"We've cut shootings and murders in half," Thomson said, by connecting with residents to "establish the fact that cops are going to perform as guardians and not as warriors."

Key to the apparent success, Thomson said, is his department's emphasis on "human contact" - officers' getting out of squad cars, walking beats, riding bicycles. "Nothing builds trust like human contact," he said. "We can't have our only interaction with the public be during moments of crisis. We need to have interaction with the public all throughout the day, and not just when times are bad."