(CNN) -- Blair Holt wanted his mother to have a pendant for Mother's Day. His father, Ronald Holt, was purchasing the gift when his cell phone rang: Blair, 16, had just been shot on a Chicago bus.
"It's just so unfair that he's not here," Ronald Holt says of his late son, Blair, pictured with him in 2005.
The dad had his left arm outstretched with his debit card in hand, the phone in the other hand.
"I felt like I had just been crucified. It was just too unreal. I just didn't want to believe it," he said, recalling that day, May 10, 2007.
Blair was killed in a hail of gang bullets when he jumped into the line of fire to save the life of a teenage girl. Four others were shot, but they survived.
A longtime Chicago police officer, Ronald Holt has spent the year since his son's killing trying to bring calm to the streets of the Windy City. He speaks to students, officials and anyone else who will listen, talking about the need for more parental involvement and better education, changing the mind-sets of troubled youth and tighter gun legislation to keep weapons from reaching thugs.
But he's also watched as the city's violence keeps skyrocketing. "It's out of control," Holt said.
In the last two weeks alone, at least 54 shootings in the Chicago area have left 15 people dead. In one horrific weekend, at least nine people were killed in 36 separate attacks. Watch as one man says, "We're sick of burying our children" »
Police dispatched SWAT officers and other specialized units this past weekend to deter potential violence. Some officers were armed with new assault weapons.
"We continue to remain aggressive in combating crime in whatever form it takes," police spokeswoman Monique Bond said in an e-mail. "Our approach is comprehensive, and increases or decreases in crime should not be based or judged on one, two or three weekends."
With warmer temperatures and summer approaching, experts who follow crime trends said violence is likely to escalate. They said the nation's economic crisis and lack of jobs in the inner city create an environment rife for crime.
"During the summer months, we will be taking an aggressive role in enforcing curfew, because juveniles are more susceptible after hours when they become victims and offenders," Bond said.
Tim White with CeaseFire, a violence prevention group that works with Chicago's gangs, spent more than 15 years behind bars for selling narcotics. He now actively tries to calm tensions among rival gangs.
"We're finding that people are losing their jobs ... and they're being desperate. They're being led into desperate situations," he said. Watch White describe, "It makes people make bad decisions" »
White and other ex-gang members with CeaseFire work the streets when they hear of problems in neighborhoods. They don't work with police because it would ruin their reputation on the streets, White said.
"We've got all different ex-gang members sitting at the table. Where we used to fight each other, now we work together to squash violence and come together for peace," he said. "It's a unique situation, but it works."
Mostly, they step in when egos of rival gangs get too big. "Don't nobody want to go to the other man and say, 'I don't want to fight you. I don't want to kill you.' "
"That's like a punk in our street life. But if someone can step in and do it for him," then gangs will accept the truce, White said.
"It gives us an opportunity to mediate situations that no one else will do."
But, he said, CeaseFire had its state funding slashed in September. In turn, the group has gone from 140 employees to 40 workers. As a result, it has resolved 44 gang conflicts this year -- way off last year's mark of 488, he said. The crunch is hindering CeaseFire's work but won't stop the group, White said.
"If we can stop a gang war this summer, then we've won," he said.
Will police armed with assault rifles help?
"Time will show if that's going to deter them," he said. "I don't think having a bigger gun is going to stop young guys from shooting each other or robbing each other for dope or robbing each other for territory."
This week, Sens. Dick Durbin and Barack Obama of Illinois asked for the Justice Department to include Chicago as part of its Anti-Gang Initiative, a federal program to enhance gang-prevention efforts. The program has provided 10 cities with $2.5 million each for anti-gang efforts.
"We are asking the Justice Department to make combating gang violence in Chicago a top priority this summer and in the future," Durbin said in a statement.
As for Ronald Holt, he has no plans to give up his fight. He said he owes it to his son.
"I have to continue to honor his heroism. He showed bravery, sacrifice and courage," he said. "That's one of the reasons I keep fighting."
His son's alleged killer was a 16-year-old gang member, as was his alleged accomplice. Both could face decades in prison if convicted.
Holt and White both said youth need to know their actions have consequences -- that the majority of violent offenders are captured and put behind bars. For White, he didn't realize that until he was in the federal pen serving hard time.
Holt said he hopes his message will reach at least one person on the fringes and that he or she changes his or her ways. He said he knows the pain of what it's like to lose a son in "one fell swoop, in the blink of an eye."
"It's just overwhelming. You just don't know what to do after that. And I think that's the one part that's extremely gripping and you can't get past: You've done all these things. Your child is a normal, typical teenager enjoying life, and then all of a sudden, here comes a devil's advocate, as I say."
Holt said people -- moms and dads, aunts and uncles, grandparents and other mentors -- need to be active in kids' lives to keep them out of trouble.
He then rattled off his favorite memories with Blair: seeing him throw his first baseball, watching him graduate from kindergarten and grade school, and witnessing him mature physically and mentally into a young leader.
This loving dad said one other moment stands out: "Watching him take his first baby steps."
Holt added, "It's just so unfair that he's not here. Just like it's so unfair that all the other children [killed in Chicago] are not here." E-mail to a friend