A five-year-old boy who was being held captive in an underground bunker in Alabama for a week has been freed by the FBI.

The little boy, Ethan, was kidnapped by a 65-year-old man, Jimmy Lee Dykes, who had taken him from a school bus after shooting dead the driver, Charles 'Chuck' Poland, on January 29.

The boy had been kept in the bunker ever since.

Officers are reported to have shot the man dead after being convinced the boy was 'in imminent danger'.

Dykes, who had been seen with a gun, had been communicating with the authorities through a ventilation pipe into the shelter

Special Agent in Charge Stephen Richardson told NBC News that they had gone in to the bunker after negotiations had broken down.

"Within the past 24 hours negotiations deteriorated and Mr Dykes was observed holding a gun," Mr Richardson said.

Dale County Sheriff Wally Olson said told reporters that Dykes was armed when officers entered the bunker to rescue the boy. He said the Ethan had been threatened but would not comment further as to how, saying only, "That's why we went inside - to save the child."

The Sheriff would also not be drawn on how Dykes died, despite it being widely reported that he was shot.

Although the authorities have not released full details of the rescue of the little boy, nearby residents say they heard 'what sounded like gunshots' at the time the FBI entered the shelter.

Jimmy Lee Dykes was described as being 'known by neighbours for his anti-government rants and for patrolling his property with a gun'. He was said to be 'ready to shoot trespassers'. He had also reportedly stayed in the tiny bunker at his home before.

Ethan has now been reunited with his mum, and was said to be 'OK' after arriving at local Flowers Hospital sitting up on a stretcher.

Five-year-old hostage boy free after FBI storm underground bunker

Alabama State Senator Harri Anne Smith praised his mum's conduct throughout the harrowing week-long ordeal, saying she had been 'incredible'.

"Mom has been incredible, she has been so brave and has always known her son would be brought home safe," Ms Smith told reporters.

Special Agent in Charge Stephen Richardson said he had been to the hospital to visit Ethan and he was 'laughing, joking, eating and doing the things you'd expect a normal five or six-year-old to do'.

Last week, sources in Alabama revealed that Ethan has Asperger's syndrome and attention deficit disorder, which could impact on how he attempted to cope with his ordeal.

"A typical five-year-old child would find this frightening. But with a child with Asperger's, which is a form of autism," State Rep Steve Clouse told CNN.

''We have to make sure that we get him back to his normal routines and that if the anxiety levels are overwhelming, to treat those."

Can you even begin to imagine what his parents have been through?