In the first draft, there were misspelled words and incomplete sentences. But after several painstaking rewrites, the authors had a version they considered letter-perfect:

"Dear Bank: We will rob this bank at 12 o'clock noon on the dot. Put $10,000 under the bank mat at the front entrance of the bank. Don't have anyone there and don't call the police or you all will suffer a fatal accident. Remember no police! Or else! Money in cash! Yours Truly, The Scorpions. P.S. This is no joke!"

On Wednesday night, the note was dropped in the night depository box of the Industrial Bank of Washington at 125 45th St. NE. The next afternoon, D.C. police waiting outside the bank picked up the note's authors--three youngsters, two 8-year-olds and another, 11--who had rolled up to the door on skateboards and lifted the mat in search of the loot. A second 11-year-old was taken into custody later in the day.

"We were expecting a terrorist or another bank robber with a new method. We were expecting an adult, really, especially after looking at the note. It was written very well. It was convincing," Sgt. Pete Mulligan of the robbery squad said yesterday.

A police official said that he didn't expect any charges to be brought against the youngsters. "We scared the hell out of them," he said. "They realize the seriousness of what they did. Their parents said they would take them home and administer proper justice in their own way."

Interviews with five of the six youngsters who admitted to police that they were involved in the scheme, the parents of four of the youngsters and police showed that an 11-year-old was the brains behind the bank robbery note. The boy said he got the idea earlier this week when he was resting on a wall outside the bank and a teen-ager asked him if he knew anyone who could write a bank robbery note. "No," he recalled telling the stranger, but his imagination began to run wild.

"I thought it could work," he said. His friends who also got involved in the prank said he was the only one who really took it seriously.

The boy with the idea said he talked his friends into writing the note, explaining to them that they could rob a neighborhood bank and make a fast getaway on their skateboards.

"We're going to rob a bank," he told one of his 8-year-old buddies. His buddy wrote the first draft thinking the idea was a joke. A 13-year-old girl said she begged to see the note and then rewrote it, enjoying the feeling of being a part of the boys' prank. An 11-year-old girl, who loves English and said she writes well, did the final editing and got a good laugh out of it--until the police stopped by her house to question her.

"I was going to cut off all my fingers on my left hand," she said, holding out the hand responsible for the attractive handwriting that made police suspect an adult extortionist.

The day after the prank, the grandmother of the boy who was the brains behind the operation berated him as he and his friends were being interviewed: "What did you think would materialize from it? You watch too much television as far as I'm concerned. It's not a day that passes that I don't try to tell you something that would benefit you in life--and look what you do."

The mother whose son wrote the first draft of the note summed up the sentiments of the other parents: "This is absolutely ridiculous. My husband told him so with the stick. He is severely punished. He can't come outdoors until the end of the summer when he has to go back to school."

Remembering how she got involved, the young lover of English said her girlfriend told her, " 'We're going to rob a bank.' I started laughing. I thought it was a joke. She showed me the note. And there were some spelling errors, so I took the note and rewrote it."

The boy who was the brains said he made up the name "Scorpions" after watching a television show, though he couldn't remember which show it was. Yesterday, the youngsters said they were sorry they got involved in the joke. Said the author of the first draft, "I learned my lesson: Don't play jokes like that because some people think it's serious."

Said the author of the final draft: "I thought they were just going to keep the letter. I didn't want to get in trouble. They joke around a lot. They be running after us, grabbing us by the neck and saying they're going to kill us. But they be just playing."

The would-be robbers attend either private or public schools in Washington. Their aspirations include racing cars at the Indy 500 and working as a firefighter, lawyer and doctor. Their parents work as construction workers, secretaries, housewives and word processors. The youngsters said they weren't in it for the money.

Still, they recalled fantasizing about splitting the $10,000 among them. One said he wanted to buy a motorcycle, another said she wanted a "whole wardrobe of Jordache jeans," one said he wanted a "brand new set of drums" and another said he wanted a Pontiac Trans Am automobile.