Oklahoma inmate Clayton Lockett apparently called out during his execution, saying "something's wrong", an Associated Press reporter on the scene has said.
Lockett later died of a heart attack, but the execution of fellow inmate Charles Warner has been postponed for 14 days.
Prison director called the execution because Lockett was still moving. At 6:37 Lockett, still moving, said "somthing's wrong."
He was conscious and blinking, licking his lips even after the process began. He then began to seize.