Reporter: It's day six of the hostage standoff. 12 feet underground in midland city, alabama, a madman is holding hostage a 5-year-old boy with autism named ethan. The bunker then is wired with... See More
Reporter: It's day six of the hostage standoff. 12 feet underground in midland city, alabama, a madman is holding hostage a 5-year-old boy with autism named ethan. The bunker then is wired with explosives. Above ground, a nation's attention has been captured by the events in this small close-knit community. We do begin this evening with that standoff playing out in the small town in alabama. Which on this day, is taking a moment to mourn its own. Bus driver charles poland is laid to rest. A hero to his community, but to his wife so much more. He was my best friend, my sweetheart. He loved those kids. Reporter: But down in the bunker, dykes is growing more and more belligerent as he begins to suspect the negotiators won't give him what he wants. In these recordings exclusively obtained by abc news, he begins to rant at negotiators. End of this day there's going to be a determination as to just exactly what the hell is going to take place. You just go ahead and send some mother down that funnel over there to their death. Reporter: The 65-year-old decorated vet is angry at the government and disdainful of the police. You're scared. You know well I'm smarter than most of you people. You know well I have the knowledge. I have the experience. I have the ability, and I have the balls to show just how corrupt this system is. Reporter: His rants have little logic, but he wants his story told, a story that he believes will spark anarchy. You know well what I'd say when I go public. Going to create chaos. It's going to create riots. People are gonna be standing up to this mother dictatorial, incompetent, self-righteous, bunch of sorry in government. And if that sorry son of a above you doesn't respond by 5:30 this afternoon, then by god I will not be talking to you no more. Reporter: As they begin day six, the nation holds its breath. Still no rescue, and the danger to ethan is increasing with every second. Law enforcement's secret eye into the bunker reveals a dangerous man on the brink. He was handling the weapons and the bomb inside the bunker on a more frequent basis. We knew that jim dykes had begun to rehearse. He had begun to prepare. Reporter: And dykes has a diabolical plan for ethan. Jim dykes relayed to the negotiators if anything happens to me, I have told ethan to pull the trigger. That meant he had told ethan to detonate the ied, the second ied that was inside the bunker. I think anyone who was aware of that was wondering, "is this it? Right now, this moment, is this it?" Reporter: But police have a plan of their own. They've been practicing a rescue in this mock bunker nearby, and they're preparing for the worst. Why? Ethan is becoming attached to dykes. Ethan is perhaps attaching in a genuinely affectionate way to the offender, which is a problem because we don't want him to run in the wrong direction if there is an assault. Reporter: The final decision of what to do would involve a gut-check moment with the fbi director. Ron hosko, who heads the fbi's criminal division back in washington, has been consulting with officers on the scene and regularly briefing fbi director mueller and attorney general eric holder. Time appeared to be running out. The commander was on the line and the situation was not a happy one. Behavioral analysis folks told us the best you can hope for is a murder-suicide. Reporter: The decision is made to take on dykes, armed with guns and bombs, head on, on his turf in a tight space. Neil tew of the state police remembers speaking to one of the fbi tactical team members the night before the assault. It was very clear to me that he was willio sacrifice his life if it meant saving ethan's. Reporter: It's noe moment of truth. I was feeling so many things. I was scared. Knowing what was waiting for them down there, it's chilling. I'll tell you, in the command post when the authorities were granted to execute the plan, there was silence. Reporter: The bunker is finally breached! And with that, dykes begins to make good on his threats, detonating the bomb in the pvc pipe. Smoke begins pouring out of the bunker entrance only three feet in diameter. The five member tactical team descends into darkness. They immediately received gunfire from mr. Dykes. Reporter: There was a ied inside the bunker as well? Yes, sir. He was in the process of trying to detonate it. Reporter: So we're talking about seconds literally meant everything? Absolutely. Reporter: It is all over in two minutes. Then, silence. It seemed like an eternity. Quiet, quiet. Think we were all praying. I vividly remember looking at kevin and saying, "you got to tell me the child is okay." The next radio traffic we heard was the child crying. As a parent, that's a up. That is a thumbs up. If he's crying, he's breathing. Reporter: Dykes is shot and killed in the confrontation. Ethan and the agents were okay, remarkably sustaining no major injuries. Do you guys believe in miracles? I believe it was by the grace of god. Reporter: But with all the joy and relief, the thoughts of the team that helped save the life of one child, turned to the man who gave his life to save them all, charles poland. How proud are you of him? Very proud. Very proud. If I had him now, probably would not let him go for a good long time. Real man, love that a man lay
This transcript has been automatically generated and may not be 100% accurate.