A Florida man convicted of raping and murdering a young girl was executed by lethal injection on Thursday while a Death Row inmate in Oklahoma was granted an 11th hour reprieve.

Bryan Jennings, 66, a former Marine, was put to death at a Florida state prison for the 1979 rape and murder of six-year-old Rebecca Kunash, prison officials said.

It was the 16th execution carried out in Florida this year, the most in the nation. There have been five each in Alabama and Texas.

An Oklahoma man who had been scheduled to be executed by lethal injection on Thursday for a 2002 murder was meanwhile granted last-minute clemency by the state's governor.

Tremane Wood, 46, was sentenced to death for the murder of Ronnie Wipf, 19, during a robbery.

The Oklahoma Pardon and Parole Board recommended clemency for Wood by a 3-2 vote on November 5, and Republican Governor Kevin Stitt granted it shortly before the execution was to be carried out at the state penitentiary in McAlester.

"After a thorough review of the facts and prayerful consideration, I have chosen to accept the Pardon and Parole Board's recommendation to commute Tremane Wood's sentence to life without parole," Stitt said in a statement.

"This action reflects the same punishment his brother received for their murder of an innocent young man and ensures a severe punishment that keeps a violent offender off the streets forever."

Wood's elder brother Jake, who died by suicide in prison in 2019, confessed to being the one who stabbed Wipf to death.

There have been 42 executions in the United States this year, the most since 2012, when 43 inmates were put to death.

An execution is also to be carried out on Friday in South Carolina, where Stephen Bryant, 44, is to die by firing squad.

Bryant pleaded guilty to killing three people in 2004, writing the message "catch me if u can" in the blood of one of his victims.

South Carolina has carried out two previous executions by firing squad this year.

Thirty-five of this year's executions have been carried out by lethal injection, two by firing squad and five by nitrogen hypoxia, which involves pumping nitrogen gas into a face mask, causing the prisoner to suffocate.

The use of nitrogen gas as a method of capital punishment has been denounced by United Nations experts as cruel and inhumane.

The death penalty has been abolished in 23 of the 50 US states, while three others -- California, Oregon and Pennsylvania -- have moratoriums in place.

President Donald Trump is a proponent of capital punishment and, on his first day in office, called for an expansion of its use "for the vilest crimes."