A gunman holding a five-year-old boy hostage in a bunker continued to keep police at bay in a siege that began when he killed a school bus driver and dragged the child away.
SWAT teams took up positions around the gunman's rural property in bible-belt Alabama, as police negotiators tried to secure the boy's safe release.
The gunman, identified by neighbours as Jimmy Dykes, a 65-year-old retired lorry driver, was known locally as a menacing figure who once beat a dog to death with a lead pipe, threatened to shoot children for setting foot on his property and patrolled his garden at night with a torch and a shotgun.
He had been due to appear in court on Wednesday morning accused of shooting at his neighbours in a dispute over a speed bump last month.
The stand-off along a red dirt road began on Tuesday afternoon US time, after the gunman boarded a stationary school bus filled with children in the town of Midland City. Sheriff Wally Olson said the man shot the bus driver when he refused to hand over the child and dragged the boy away.
"As far as we know there is no relation at all. He just wanted a child for a hostage situation," said Michael Senn, a pastor who helped comfort the traumatised children after the attack.
The bus driver, Charles Poland, 66, was hailed a hero who gave his life to protect the 21 children on the bus.
The boy's classmates, their parents and other members of the small community gathered in several churches and held a candlelight vigil in the town square last night to pray for Mr Poland and the boy's safety.
Authorities gave no details on the siege and it was unclear if Dykes made any demands from his underground bunker, which resembled a tornado shelter. The sheriff said negotiators continued talking to the suspect and "at this time we have no reason to believe that the child has been harmed".
About 50 law enforcement vehicles were clustered at the end of a dirt road near where Dykes lived in a small mobile home. Nearby homes were evacuated after authorities found what was believed to be a bomb on his property.