In an incident that was described variously yesterday as "an attempt at dialogue" and "trespassing," about 60 members of a group opposed to Prince George's County school closings disrupted a school board work session Tuesday night in Upper Marlboro.

Members of the Coalition for Quality Education and three county council members appeared unexpectedly at an unannounced school board work session on the budget at about 10:30 p.m. to demand that board members discuss school closings, school officials said yesterday.

When some of the board members and assembled school staff attempted to leave the board's meeting room, p.m. to demand that board members said, the protestors blocked the exits to the building. The board members were able to leave the building, but not before police had been called to the scene, participants in the meeting said.

Eventually, five board members agreed to remain and talk to the protestors, and two-hour meeting ensued. "I don't know if I would call it a dialogue, but at least we sat down together," said a leader of the group, Dan Gallow, yesterday.

Gallow said that the protest grew out of a meeting of the coalition in Largo Tuesday night that was attended by council members Parris N. Glendening, Sue V. Mills, and Floyd E. Wilson, Jr., who generally support the coalition's goals of halting or at least delaying consideration of school closings.

As the group discussed its frustrations in lobbying school board members, Gallow said, "someone suddenly suggested that we just show up at the meeting they were having. We just piled in our cars and went."

Three school board members were irritated enough by the group's arrival and demand for an audience to walk out.

"I was getting ready to leave anyway, but I was outraged when they trid to block the exits," said board member Chester E. Whiting, who walked out. "I was not going to be held hostage by anyone."