ORLANDO, Fla. (AP) _ As a woman kept a bedside vigil in North Carolina for a comatose teen-ager identified as her son, the father of a schoolmate of the unconscious youth grieved for his runaway son at a funeral home here.

Then Frank Hegler looked in the casket and nearly went into shock.

''I said, 'That's not my kid,''' Hegler recalled. ''I'm in a nervous breakdown, it's that bad. We made all the arrangements to bury the wrong body.''

The casket contained the body of Timothy Lee Vanderbrook, 16. The youth in a coma in a hospital at Lumberton, N.C., was his schoolmate, 17-year-old Robert Hegler. Both were involved in a traffic accident near Lumberton a week ago in a car they allegedly had stolen.

The mix-up occured when emergency workers found Robert Hegler's wallet in young Vanderbrook's pants pocket, said Jeanne Stevens, spokeswoman for Southeastern General Hospital in Lumberton.

''It's been like a nightmare and I still haven't faced it,'' said Vanderbrook's mother, Gloria Headley of Orange County, outside Orlando.

Mrs. Headley said she had suspected that the unconscious boy wasn't her son. But hospital employees convinced her otherwise because the teen-ager's face was so badly swollen.

Mrs. Headley's vigil ended when the mix-up was discovered last week, and her place has been taken by Hegler's mother, Delores Evans.

''This has been horrid,'' said Mrs. Evans, Hegler's ex-wife. ''Something like you see in movies. I doesn't happen to you. ... I can hardly explain it. I'm just numb.''

Police said the two youths stole a new car May 26 and headed north.

That afternoon, a Robeson County, N.C., deputy spotted the car and thought it was being driven suspiciously, but when he flashed his lights to pull it over the driver sped up. The ensuing chase hit speeds of up to 120 mph.

Near Lumberton, the car swerved to pass a state trooper and went out of control, flying 60 feet in the air, crashing and flipping, throwing the teen- agers out.

One was declared dead on arrival at the hospital. The other arrived comatose.

''I can't be happy,'' Hegler said of his son's survival. ''I don't know if he's going to make it or not.''

Timothy Vanderbrook was buried Friday.