First lady Michelle Obama visits with students at Harper High School in Chicago on Wednesday. (Nancy Stone, Chicago Tribune / April 10, 2013)

Obama was the keynote speaker at the luncheon, set up by Emanuel to garner support for an initiative called Working Together for Safer Communities, Brighter Futures. The campaign, launched in February, calls for business leaders and others to raise $50million over the next five years to create or expand community programs for at-risk youths. Already, the group has received pledges of $33 million.

In the audience were about 800 business, government, civic and faith group leaders, including restaurateur Charlie Trotter; former Detroit Pistons point guard Isaiah Thomas; Tio Hardiman, director of CeaseFire Illinois; police Superintendent Garry McCarthy; Illinois Attorney General Lisa Madigan; and Cook County Board President Toni Preckwinkle.

"This is not a gap of geography, it's a gap of opportunity," Emanuel said, referring to the lack of resources available to young people in some Chicago neighborhoods.

Jim Reynolds, chairman and CEO of Loop Capital and head of the Public Safety Action Committee set up by Emanuel to lead the fundraising effort, said the first lady's appearance was like "adding a little bit of rocket fuel."

In choosing Harper High School for the visit, the White House noted that 29 current or former students there had been shot in the last year, eight of them fatally.

Outside Harper, students lingered in the neighborhood hoping to get a glimpse of the first lady's motorcade. Some expressed disappointment that she did not address the entire student body.

But those who got to meet her said they left with the feeling that someone really cares about them.

"I shared with her that I would stay inside, in 85-degree sunny weather, because I'm scared walking down the street. I fear for my life. I feel today could be my last day," said Ronald Ligon, 16.

"She said she would do everything in her power to stop the violence that goes on. I know that she really does care. Now I feel this is a new beginning for me."