Three maximum security inmates, including two convicted murderers in a gangland-style slaying, sawed their way out of jail early yesterday, overpowered an airport attendant and escaped in a twin-engine plane.

Two of the men were said to have had some flying experience. The Piper Comanche was capable of flying 800 to 1,000 miles without refueling. The Federal Aviation Administration issued a nationwide alert.

Authorities said the escapees had nearly a three-hour head start.

Douglas County Sheriff's Deputy Joe Thornton said it was uncertain how C. Michael Anderson, 26; Peter Hochstein, 24, and Dan Sheppard, 22, got out of their cells and obtained a saw blade to remove two bars on a window in the jail's recreation unit.

Anderson and Hochstein was convicted of first-degree murder for the 1975 slaying of Omaha realtor Ronald Abbound. Sheppard was being held for a probation violation and on a federal misdemeanor warrant.

Thornton said the men used a rope fashioned from bed sheets to escape from the top of a six-story courthouse in Omaha. They stole a car and drove to Millard Airport where they forced a night attendant to fuel the plane. Then they took off.