Mr Pack said that officials found an explosive device inside the pipe, as well as another device inside the bunker.

BBC: Alabama hostage-taker died 'in firefight'

As it turned out, authorities' decision to rely on every tool at their disposal was a wise one: Dykes had planted an explosive device in a ventilation pipe he'd told negotiators to use to communicate with him on his property in the rural Alabama community of Midland City, and also placed another explosive device inside the bunker, the FBI said in a statement late Tuesday.

WSJ: Military tactics, arms, helped rescue Ala. hostage

After the rescue, authorities found the pipe packed with explosives along with another explosive inside the bunker itself, authorities said.

CNN: Inside the bunker: From storm shelter to boy's prison