A former prison nurse helped her husband escape Tuesday by fatally shooting a correctional officer who was escorting him outside a county courthouse.

An extensive search was under way for the pair, identified as George and Jennifer Hyatte, and authorities were trying to determine if an accomplice was involved, Roane County Sheriff David Haggard said.

Jennifer Hyatte (search) had been fired from her job at a prison in Tiptonville because of her relationship with George Hyatte (search), a state official told The Knoxville News Sentinel. She worked for a state contractor, Correctional Medical Services.

Helicopters circled over the town of about 6,000 people, which county Emergency Management Agency (search) spokesman Scott Stout called "small town USA." Schools were locked down and roads around the courthouse were closed.

Kingston Police Chief Jim Washam said authorities were preparing murder charges for both suspects.

"We do have leads coming in on possible whereabouts, possibly some family members that may be hiding them out. We're trying our best to coordinate those," Washam said. "Right now, we can't say if they had any help."

The officer, Wayne "Cotton" Morgan (search), was shot in the stomach and was airlifted to University of Tennessee Medical Center (search) in Knoxville, about 30 miles east of Kingston, but hospital spokeswoman Lisa McNeal said he had died.

Tennessee Gov. Phil Bredesen put out a statement that said he was "outraged over the senseless and cold-blooded murder" and he vowed to "spare no effort to bring these criminals to justice."

George Hyatte, who is two years into a 35-year sentence at Brushy Mountain Correctional Complex (search) for aggravated robbery and aggravated assault, was at the courthouse to plead guilty in a deal with prosecutors over an armed robbery charge, Washam said.

The shooting happened about 10 a.m. as officers from Brushy Mountain were loading Hyatte and other inmates into a prison van parked outside the courthouse. Hyatte was handcuffed and shackled at the feet, witnesses said.

Washam said a woman driving a Ford Explorer sport utility vehicle pulled up behind the van.

"Mr. Hyatte hollered 'Shoot him!' She opened up fire on the officers, hitting one in the abdomen," Washam said. The woman was armed with a handgun and fired several times, he said.

Witness C. G. Gray said he and his wife were in the parking lot about 50 feet away from the prisoners when they heard shots. Gray said Morgan, who wasn't wearing a protective vest, never got his gun out of his holster but another guard, whose name wasn't immediately available, did return fire.

"The other officer did a get a shot off, apparently striking one of the individuals," Washam said.

The SUV sped off but was found abandoned soon after with blood on the driver's side, leaving officials to think the woman may be injured, Washam said.

Several vehicles in the parking lot were struck by the shots and their windows shattered.

George Hyatte, 34, was described as black, 5 feet, 5 inches tall and 140 pounds and last seen wearing a blue denim prison uniform. Jennifer Hyatte was described as white, 5 feet 4 inches and 140 pounds. Her age wasn't available.

Authorities were searching for a gold Chevrolet Venture van that the two were believed to be using after dumping the SUV.

The wife was in the courtroom as Hyatte entered his plea, Washam said. Attorney Chris Cawood, who was in court right before Hyatte's case, said two spectators in the courtroom ran out when the prisoner pleaded guilty.

Hyatte has a history of escape, Washam said. Several years ago he escaped from local authorities and was a fugitive for about a day after a holdup at a drive-in market.

Hyatte was serving two consecutive 15-year sentences for robbery charges and a five-year sentence on top of that for assault in a case out of Rhea County, state prison officials said.

Rhea County Sheriff's Department spokesman Jeff Knight said George Hyatte has family in the Dayton area — which is about 40 miles southwest Kingston — but they don't want to have anything to do with him.

"He is extremely violent, and he has no care or concern on what he does to anyone," Knight said.