Four-month-old twin girls who were joined from their chests to their abdomens were successfully separated in a six-hour surgery with no complications, doctors at Children's National Medical Center (search) in Washington, D.C., announced Saturday.

Jade and Erin Buckles (search) of Woodbridge, Va., were in critical but stable condition, according to a hospital statement.

"After months of planning for many different scenarios, the separation went very smoothly," lead surgeon Gary Hartman said in the statement.

The surgery began at 10:10 a.m. Jade and Erin were separated at 12:30 p.m., and individual surgery to close gaping wounds in each girls' torso continued for more than three hours.

"It has been a long journey and we know we are not out of the woods yet, but we are extremely relieved that the surgery was successful," said the girls' parents, Kevin and Melissa Buckles.

The girls were born Feb. 26 at the National Naval Medical Center in Bethesda, Md. They shared a liver and one of the babies' hearts rested horizontally, protruding into the other girl's chest cavity.

The hospital has scheduled a news conference for Monday.