MIDLAND CITY, Ala. (AP) -- The FBI says the Alabama man who held a 5-year-old boy captive in an underground bunker for nearly a week engaged in a "firefight" with SWAT agents before he was killed during a rescue operation.

Special Agent Jason Pack said in an email that it also appears 65-year-old Jimmy Lee Dykes "reinforced the bunker against any attempted entry by law enforcement."

Pack said bomb technicians found two explosive devices Tuesday on the property. He said one was inside the bunker, the other was located inside the plastic pipe through which he had been talking with negotiators

Officers killed Dykes on Monday, six days after he boarded a school bus, fatally shot the driver and abducted the young boy.

The law enforcement official briefed on the situation said Monday that Jim Dykes, the man who abducted the boy from a school bus after fatally shooting the bus driver, is dead. The official spoke on condition of anonymity because the person was not authorized to discuss the situation.

Fearing child hostage was in danger, FBI stormed Ala. underground shelter.

Earlier Monday, officials had said they had been sending food and medicine to Dykes and the boy in the bunker.

The boy has Asperger's syndrome and attention deficit hyperactivity disorder.