D.C. school officials said yesterday that they have fired 23 bus drivers and attendants who did not show up for work Monday, when about 260 drivers and attendants called in sick.

David Gilmore, the District's court-appointed school transportation administrator, said he made the decision because the workers failed to tell a supervisor that they would not be coming to work, which constituted abandonment of their jobs. He said more people might soon be fired or face other disciplinary action.

"I think folks have to understand that this is a job," Gilmore said. "This is work. This isn't playtime. It isn't something that you come to work when you feel like it and don't when you don't."

On Monday, nearly 20 percent of the city's 692 school bus drivers and 714 attendants -- whose job it is to ferry special education students to and from school -- failed to show up for work in what school officials called an illegal union sickout.

George Johnson, executive director of District Council 20 of the American Federation of State, County and Federal Employees, which represents Local 1959, the drivers' and attendants' union, denied Monday that a strike or work stoppage had been called, noting that it is illegal for public servants to strike. But he complained that the employees have been dealing with chronic payroll problems that he said the school system has not addressed.

Johnson did not return a phone call last night seeking comment.

Gilmore said last night that the 23 fired employees were not among those who called in sick and that his decision to dismiss them was not connected to the alleged sickout.

"These were 23 people who simply did not come to work on Monday and never bothered to call to say they wouldn't be there," he said.

He said that he has required everyone who called in sick Monday to present a doctor's note justifying the absence and that he is reviewing that documentation. He said that he did not know how many of the absent workers had brought in a doctor's note but that he would review each case and decide on an individual basis how to proceed.

Roxanne Evans, spokeswoman for the school system, said that Monday's situation "was a major disruption to parents" -- affecting about 13 percent of the bus routes -- and that employees would not be allowed to violate rules with impunity.

Gilmore said bus drivers and attendants have been fired in the past for failing to show up for work without notification.