Conjoined twins born Oct. 25 have been separated by surgeons at Children's Hospital at OU Medical Center during an operation that lasted a little more than three hours on Monday.

Hospital spokesman Allen Poston said Preslee Faith Wells and Kylee Hope Wells, who had been joined at the chest since birth, were separated at 12:14 p.m., a little more than an hour after the operation began. The process involved splitting the girls' livers and a tissue bridge that connected them.

After the girls were separated, they were placed on their backs on separate beds in the operating room so that the surgical team, led by David Tuggle and Cameron Mantor, could begin the closing process, Poston said.

The surgeons, who said before the operation that it might last four to six hours, finished shortly after 2 p.m.

"Everything went well," Poston said.

The girls, believed to be the first known American Indian conjoined twins, are listed in critical condition and are in the hospital's neonatal intensive care unit, where they've been cared for since their birth.

Poston said the twins' parents, Stevie Stewart and Kyle Wells of Calumet, were "very emotional" during the surgery and were surrounded by about 25 family members and friends in a waiting room at the hospital.

Poston said that after the twins have some recovery time, their parents will be able to see them later Monday.

"This is an exciting day for us," Wells said in a statement issued by the hospital. "We are very thankful to the physicians and surgical staff at Children's Hospital. We appreciate all the prayers and hope people will keep us in their thoughts over the next few weeks."

Doctors have said the Wells twins have a good chance at survival because they had separate hearts and don't share any major blood vessels.

Tuggle also was part of the team that separated a pair of conjoined twins born 22 years earlier in Oklahoma. Those two twins, Faith and Hope Cox, now are healthy young women.

Tuggle has said conjoined twins are rare and occur in about 1 in 600,000 births in Oklahoma. He said the condition happens soon after conception because of an error in cell division and is random.

Doctors learned of the Wells twins' tissue connection during a routine ultrasound exam done when Stewart was 20 weeks pregnant. The babies were born at 34 weeks via Caesarean section at Children's Hospital.