By Syma Chowhry

PHILADELPHIA (CBS) – It’s a day of reflection and hope.

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An event commemorated the second anniversary of the building collapse that took place on the corner of 22nd and Market Street.

Family and friends of the victims gathered to remember those who lost their lives two years ago.

Six people were killed and 14 injured when crews were demolishing a vacant building next to a Salvation Army store.

One of those was Nancy Winkler’s daughter, Anne.

“Anne’s death has left a terrible void in our family which can never be filled,” Nancy says.

Winkler is on the committee that is trying to set up a memorial park at the fateful location.

Earlier this year, an eight foot replica was unveiled. It has the names of the victims along with a piece of colored glass picked by their families.

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For Winkler, the memorial is a place for reflection, but also a reminder to prevent future tragedies.

“Philadelphia can and must do better,” she says. “Our mission is to make sure that no other family will ever suffer the terrible pain that we know.”

Fifty-year-old demolition contractor Griffin Campbell and 43-year-old subcontractor Sean Benschop have been charged with third-degree murder. The trial is set to start in September.

Mayor Nutter says the city has made changes since the collapse.

“Investing more resources, personnel and training. L&I was brought under the umbrella of the deputy of safety, making a point that this is, in fact, a public safety agency,” Nutter explains.

The Mayor also says he is devoted to expanding the memorial to the next lot.

“I have long held the view that nothing, nothing, nothing should ever be built on this entire site,” he says.

Officials say they need $1.3 million to build the memorial park, and they already have more than half of that.

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At the event, the mayor also announced a $300,000 donation from the city, inching them even closer to their goal.