ATLANTA - Two Georgia inmates who killed their guards and escaped from a prison bus have stolen a second vehicle as they try to stay ahead of a massive manhunt, a sheriff said Wednesday.

Donnie Russell Rowe, serving life without parole, and Ricky Dubose, who has prominent tattoos on his face and neck, took a white pickup truck from an industrial site sometime between 6 p.m. Tuesday and 6 a.m. Wednesday, potentially enabling them to get hours away before the theft was discovered, said Putnam County Sheriff Howard Sills.

Sills described the fugitives as violent repeat offenders and extremely dangerous, having taken the guards' 9 mm pistols. He urged anyone who sees them to call 911 immediately.

"They just murdered two corrections officers in a brutal fashion," Sills said. "They're not concerned with anything regarding human life."

Immediately after the killings early Tuesday, the pair carjacked a driver who happened to pull up behind the bus on a rural highway. They took off with the Honda driver's phone, leaving 31 other inmates locked in the bus with the two dead guards, and were gone by the time help arrived.

Hours later, authorities converged on the small city of Madison, about 25 miles to the north, where they determined the fugitives had ransacked a house around 10:30 a.m. Tuesday. Sills said the fugitives took some food and likely some clothes, since they left their prison uniforms behind.

Authorities put up roadblocks, only to discover Wednesday morning that the pickup had been stolen, about 9 miles from the burglary. Now authorities are searching for a 2008 white Ford F250 pickup truck with the Georgia tag BCX-5372. The Honda was found later, intentionally hidden in woods not far from the burglarized house, Sills said.

Sills agreed with reporters that Dubose will have trouble hiding his prominent tattoos, which include crowns above his eyebrows, a star below his right ear and graffiti-style letters all across his neck. Sills said Dubose also has "ghost" tattooed on his right forefinger and "face" on his right pinky finger - signs of membership in the Ghost Face Gangsters.

Both escaped inmates were serving long sentences for armed robbery and other crimes. The Department of Corrections website indicates Rowe has been serving life without parole since 2002, and Dubose began a 20-year sentence in 2015.

The inmates have been cellmates more than once in Georgia's prisons, had known each other for "quite a while" and may have planned the escape together, Department of Corrections Assistant Commissioner Ricky Myrick said. He wasn't sure whether they were cellmates at Baldwin State Prison immediately prior to the escape.

Baldwin State Prison officers Sgt. Christopher Monica and Sgt. Curtis Billue were driving 33 inmates between prisons when Rowe and Dubose overpowered them and then used the guards' guns to kill them around 6:45 a.m. Tuesday, authorities have said.

The other inmates have been questioned and a camera on the bus recorded the guards being shot, but corrections officials have not explained to the public how the pair managed to get through the inmate compartment's normally locked door.

"They were inside the caged area of the bus," Sills said. "How they got through the locks and things up to that area, I do not know."

The sheriff said he's watched the bus video on a cellphone and couldn't immediately tell which inmate fired the fatal shots.

Monica, 42, and Billue, 58, were both transfer sergeants at Baldwin State Prison. Monica had been with the Georgia Department of Corrections since October 2009 and Billue since July 2007.

"Officer Billue's family asks for prayers for all of those who are now placing their own lives at risk to bring these men to justice and asks anyone who has information that may assist in apprehending these perpetrators to please contact law enforcement," Jim Green, an attorney who's speaking for the Billue family, said in an email Tuesday.

The reward for information leading to their arrest grew Wednesday to $90,000, contributed by multiple agencies, Sills said.

The FBI announced plans to hold a news conference in Madison on Thursday along with state and local law enforcement to provide a "comprehensive update" on the investigation.

Sills said it's likely the pair has left the Madison area. Many law enforcement officers from local, state and federal agencies are hunting for them.

"They've certainly had time to get out of the state," Sills said.