MIDLAND CITY, Ala. — As FBI and police negotiators sought for days to coax an Alabama man into freeing a kindergartner held hostage in an underground bunker, the captor was planning for violence, authorities say.

He rigged the bunker with explosives, tried to reinforce it against any raid, and when SWAT agents stormed the shelter Monday to rescue the boy, Jimmy Lee Dykes engaged in a firefight that left the captor dead, the FBI and officials said.

After the nearly weeklong hostage ordeal, relatives say the boy who turned 6 on Wednesday appears to be doing well and is back at home. He was seized off a crowded school bus Jan. 29 after authorities say the 65-year-old gunman shot the driver dead and took the child to the bunker, where he was held until Monday's rescue.