By Cherri Gregg

PHILADELPHIA (CBS) — The double shooting at a North Philadelphia homeless shelter on Sunday is sparking safety concerns. The shooting claimed the life of one shelter employee and injured another.

Now, some who serve the homeless community are asking for change.

“I would like to see this tragedy be used to say what is wrong with this homeless shelter system,” says J. Jondhi Harrell, director of the Center for Returning Citizens.

Harrell says he is the social worker that placed 32-year-old John Brock at Station House.  Brock turned himself into police on Monday.  He is accused of using a gun to kill 43-year-old Edward Barksdale and wound 26-year-old Lamont Barham.  Police say Brock returned to Station House Sunday on a mission to execute the employees that helped escorted him out of the building days before, when he was evicted following a drunken episode.

“When I went down there Sunday morning he was the last person I thought would be involved in this,” says Harrell, “this was totally out of character.”

Harrell admits Brock had several run-in with staff at Station House, but says Brock wanted to change his life.  He believes individuals like Brock who are dealing with addiction and homelessness can get desperate and act out against whoever is nearby.  This time, sadly, Barham and Barksdale were the victims.

“I in no way condone what happened or Brocks actions,” says Harrell, “but these are individuals who are in difficult situations.”

Reporter: “Nothing like that has ever happened here has it?

Richard McMillen: “Well, we have had situations.”

Richard McMillen runs Sunday Breakfast Rescue Mission, a non-profit that runs one of the city’s largest independent emergency shelters for me.  He says they can house up to 250 men a night.  McMillen recalls that Brock stayed at the Mission a couple of years ago without incident, but notes violence inside shelters is not uncommon and quickly escalates.

“More often it’s between the homeless people themselves,” he says, “but we are always concerned for our staff and for our residents.”

McMillen recalls a recent incident where a man high on drugs tried to break through their metal doors.

“It was a little scary,” he says.

Luckily, the Mission uses double security doors, surveillance cameras and wand metal detectors that helped keep them safe. They also require that residents check their belongings to keep them secure and out of the sleeping areas.  He says even with tight security, word of Sunday’s shooting at Station House had staff asking questions about the circumstances.  They want to make sure what happened there, does not happen at the Mission.

“We are having discussions among staff,” says McMillen, “we are also conversations with our guests, we want to keep them aware and informed.”

On Sunday, former Mayor W. Wilson Goode, volunteer CEO of SELF Inc. which runs Station House, told reporters the shelter trains its staff on how to deal with the homeless populations and uses security measures, including pat downs, for safety.  However, Brock avoided security by entering the shelter with food delivery workers.

Today the Office of Supportive Housing issued a statement:

“The Office of Supportive House is evaluating security measures at Station House and at all city shelters to determine whether additional safety measures are needed.”

In the meantime, Harrell’s Center for Returning Citizens is providing Brock a free lawyer.  He says he hopes the public does not focus on Brock’s wrongful actions, but instead looks at the shelter system itself to make change so that a what occurred on Sunday never happens again.

“This is dangerous work,” says Harrell, “we are dealing with people in very difficult situations, but we thrive on this work. We will keep going.”