Shortly after 10 a.m. Thursday, Army Staff Sgt. Jackie O'Neal, a computer operator in the Pentagon, got a phone call summoning her to the guard's desk.

"I thought it was something to do with my job," said O'Neal, 26, "because this is a restricted area and people leave packages or need to be let in. This marshal was standing there and he had a big smile on his face and he said, 'Hi!, Are you Jackie O'Neal? You're under arrest.'"

O'Neal was one of 28 Pentagon employes, including a Navy captain, who were arrested by 15 U.S. marshals in a crackdown on parking violations in the Pentagon's giant parking lots, the largest operated by the General Services Administration in the metropolitan area. A GSA spokeswoman said 25,000 tickets are issued there each year.

The 28 were taken to the Pentagon's center courtyard in view of hundreds of coworkers, frisked, loaded onto windowless buses and arraigned before a U.S. magistrate in Alexandria on charges of violating the Pentagon's parking regulations.

"I wanted to keep it as low-profile as possible," said U.S. Supervisory Marshal Roger Ray of the raid, which nevertheless was taped by at least one local telvision station.

Ray said he chose the very visible central court, called "the hub of the wheel" by one Pentagon official, solely becuase of its accessability to all parts of the building.

Ray said he planned the raid because of the thousands of unpaid parking tickets incurred by an estimated 500 Pentagon employes who are habitual scofflaws. Ray said that many park in visitor parking lots close to the complex rather than in designated lots that may be as much as a mile from the building. "These tickets just cause tons of paper work and we had to do something," he said.

O'Neal, who had 13 unpaid parking tickets and was fined $195, took a dim view of her day in court before magistrate Quin Elson.

"We had to sit on that bus which didn't have windows or anything for two solid hours," said O'Neal who was wearing a uniform. "It was so hot in there that we could all have wrung out our clothes. And they refused to let anybody use the restroom."

O'Neal said that when the group arrived in Alexandria, "We were told by the judge that some of us would be going to jail. I was really scared. I'm a single parent and I didn't know what to do about my little girl who was in nursery school in Temple Hills."

Witnesses to what one Army officer jokingly called "the great Pentagon bust" said that some of the arrested employes were laughing and joking until they were spreadeagled and searched by marshals before boarding the two buses for the trip to the courthouse.

"They weren't laughing when they got to my court," said Elson, who sentenced several people to 90-day jail terms and then suspended the sentences. Elson suggested in court that if more tickets were paid, "Mr. Carter would have his B-1 bomber."

"It's an extreme problem," said Elson, referring to parking violations at the Pentagon's 10,000-space parking lots, "I think all of us, particularly those employed by the federal government, should be responsible citizens."

"It's about time the courts did something, he continued, "I was not harsh." Elson said that many employes, some of whom owed about $200 in fines, were given up to a month to pay.

Ray said that 10 of the 28 arrested, who were preselected at random, had only one outstanding ticket.

"Judge Elson was very rude," said O'Neal, whose coworkers took up a collection to pay off her fines which date back to 1976. "He told me that if I get another ticket of any kind within a year I'll spend 90 days in jail.

"If I had shot someone or robbed a bank I could understand it, but treatment like this for a parking violation is really ridiculous. Parking is a real problem here. When you get here you can't get a permit right away, so you're put on a waiting list. You've just got to take your chances."

Army spokesman Courtenay Welton said that GSA guards patrol each lot daily to make sure cars are parked in the proper lots. "The bigger the carpool the closer you get," said Welton, who noted that there is close-in parking for high-ranking officers and employes who work unusual shifts.

Ray said that Pentagon employes had been given fair warning. A month ago, he put an ad in the Pentagram, a widely-circulated newsletter in the Pentagon stating that a special office, now closed, was being established for employes to pay parking fines.

According to Ray only 15 people showed up to pay fines which are $5 to $10 when issued and then rise to $15 and then to $50.

"I haven't decided if I'll go back to the Pentagon or not," Ray said yesterday. "There has been a lot of response today telephonewise, with people calling up and asking about tickets. One sergeant called up and asked about his whole office staff."