Webster's defines mensch as "a person of integrity and honor."
Snider called Katz a "wonderful human being. He gave everything he had to make a difference. He cared about everyone."
Katz donated millions to Camden - he grew up in the Parkside section - and his alma mater, Temple University.
"He gave generously of his time and money to help so many. I know it gave him such a thrill to impact the lives of so many throughout our region," Snider said.
When Snider was contacted later in the day, his voice cracked with emotion.
"Lewis Katz was one of my closest and dearest friends," said Snider, who said he was too emotional to continue the interview.
Katz made his fortune by investing in the Kinney Parking empire and the Yankee Entertainment and Sports (YES) Network in New York. He had flown to Massachusetts to attend an education-related fund-raiser.
At Yankee Stadium on Sunday, there was a moment of silence before the Yankees played the Minnesota Twins.
In a statement, Lou Lamoriello, president and general manager of the New Jersey Devils, said he was shocked to hear the news.
"I worked for Mr. Lewis Katz with both the Devils and New Jersey Nets, and experienced firsthand the influence he had on both organizations," he said. "Lewis was extremely active in the business community, a philanthropist, and a family man. On behalf of the entire Devils organization, our thoughts and prayers go out to the Katz family, as well as the loved ones of the other six casualties."
Adam Silver, the NBA commissioner, called Katz a "visionary businessman who touched the lives of so many with his tireless pursuit of innovation and enterprise, as well as his deep commitment to his family, friends, and community."
Under Katz, the Nets reached the NBA Finals in 2002 for the first time in franchise history.
Fred Turoff, coach of the Temple men's gymnastics team, wrote on the team's Facebook page: "After the cuts to the varsity teams were announced last December, Lew pledged his personal support for the men's gymnastics team at Temple to help finance its operations next year. TUMG offers condolences to his family in this difficult time."
Former Phillie Shane Victorino, whose foundation honored Katz in 2012 for his charity work, tweeted: "Love you like a dad! You taught me the value of helping others and giving back! Numb right now. Gonna miss ya pal."
In April 2012, during a Boys & Girls Club event at the Prudential Center in Newark, N.J., Katz beat Shaquille O'Neal in a free-throw-shooting contest, hitting 7 of 10 shots to the ex-NBA star's 6 of 10.
Yankees general partner Hal Steinbrenner, 76ers CEO Scott O'Neil, and Nets minority owner Bruce Ratner also were among those releasing statements expressing condolences to the Katz family.