"Drug dealers have been killing our city for years and years and years, and it's time for all of us to rise up and take action," O'Malley told WBAL radio hosts Chip Franklin and Rob Douglas.
The mayor also criticized Franklin and Douglas for blaming the city's troubles on "nitwit politicians."
About 10:25 a.m., O'Malley was leaving a conference at the Wyndham Inner Harbor Hotel when he heard the WBAL show on his car radio. He ordered his driver to head to the studio.
After announcing to the surprised studio managers that he wanted to respond on the air, O'Malley sat down next to a microphone. In a tense and strained voice, the mayor explained that he was slow to say much publicly about the deaths of Dawson and her children because the cause of the fire was still under investigation.
He added that he was furious that the clues pointed toward the possibility that a drug dealer may have set the fire in retaliation for Dawson reporting his illegal activity to the police.
"If indeed this was an intentional firebombing ... all of us should be outraged. I was near tears all day yesterday, and I couldn't stop thinking about my four children all yesterday," O'Malley said. "I barely got through a moment yesterday without thinking of those kids."
He called for residents to fight back against drug dealers.
"People have a very easy time blowing off homicides in the city of Baltimore," he said. "But the fact of the matter is ... these kids had absolutely no culpability in what happened to them. And I am going to do everything in my power to make sure the sacrifice they made was not in vain."
For about a half-hour, the mayor and the hosts engaged in a series of tense, sometimes bitter exchanges. This appeared to be in part because O'Malley, who was to appear every second week on a WBAL show called Mike Time with the Mayor, had canceled about half his appearances since February because of scheduling conflicts, including his son's birth this month.
But the mayor's anger also erupted when a caller to the show suggested that O'Malley was absent while drug dealers had seized control of the city. The show's co-host, Douglas, relentlessly needled the mayor, criticizing police Commissioner Edward T. Norris and implying that O'Malley was a "nitwit" who had been hiding from the public.
"If Baltimore residents are going to keep electing the same nitwits year in and year out, they get what they deserve," Douglas said.
O'Malley fired back: "I think you do the body politic a grave disservice when you blame these heinous acts on the so-called nitwit politicians."
Douglas tried to compliment the mayor, saying that O'Malley's shaking hands and teary eyes "shows the passion you have for the city."
O'Malley didn't take it well. "On that note, that probably is a good way to exit," he said. "And gentlemen, if you enjoyed that, come outside after the show, and I'll kick your ass."