FORT MYERS, Fla. (AP) _ Authorities were searching Sunday for a convicted murderer who fooled prison officials into thinking he was a paraplegic before diving out of his wheelchair to overpower a guard and escape.

Robert Blackmon, 43, who was serving a life sentence at Avon Park Correctional Institution for second-degree murder in the 1978 slaying of his wife, took the guard, a medical technician and a fellow inmate hostage, but they escaped, prison officials said.

Blackmon was being returned to prison from a hospital visit Friday when he jumped from his wheelchair and grabbed the gun of a prison guard accompanying him, prison officials said.

''Somehow, the guard turned around momentarily and he (Blackmon) dove out of his chair on top of the officer and was able to get the weapon,'' Avon Park superintendent Dale Landress said.

That Blackmon was able to stand came as a shock to many prison officials. Landress said most of the prison staff had believed Blackmon, eligible for parole in 1994, was a paraplegic.

The inmate was injured during a tour in Vietnam, but apparently not as severely as authorities believed.

''We've never seen him walk here,'' Landress said. ''We've heard rumors that he could move his legs, that was all.''

Blackmon had been taken to a hospital in nearby Sebring for an examination after telling officers he had injured himself falling out of his wheelchair, Landress said.

After seizing the other two hostages, Blackmon exchanged clothes with the guard and forced the other prisoner to drive the four of them to Fort Myers, where they were involved in a minor car accident late Friday.

When Blackmon got out of the prison van to inspect the damage, the hostages drove away. ''They took off and left him standing there,'' Landress said Saturday.

After being stranded by his hostages, Blackmon persuaded the driver of the car that had been hit to drive him to a store. When that driver got out, Blackmon stole the Chevrolet, authorities said.

The Lee County Sheriff's Office continued to search for Blackmon Sunday, with the rest of the state law enforcement agencies warned to be on the lookout for him, said Cpl. Pete Balfour of the sheriff's department.