The graduation at Walter G. O’Connell Copiague High School was held Thursday night, lacking several dozen seniors who were barred from the ceremony in connection with vandalism at the school and days after some made last-minute pleas to walk.

In the 90-minute ceremony, scant mention was made of the missing students. Valedictorian Tomasz Solecki appeared to address them when he said, “Some of us, we did it. Some of us, we didn’t do it. But it is what it is.”

Parents interviewed by Newsday said more than 30 seniors were unable to attend graduation ceremonies. Several dozen chairs were empty on the high school’s football field, where the ceremony was held.

School officials last week said some students broke into the high school at 2 a.m. on June 9 and used eggs and shaving cream to deface parts of the building, ransacked an assistant principal’s office, and smashed a projector used for instruction.

Students climbed through a second-story window to enter the school and activated an alarm system that alerted Suffolk County police of the break-in. Security footage recorded the vandalism.

School board president Brian J. Sales said at Monday night’s Board of Education meeting at Copiague Middle School that the decision to bar a group of seniors from graduation was “agonizing,” but called the behavior “unacceptable and inexcusable.” Across the street from where the meeting was held, students protested in the rain, chanting, “Let us walk.”

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However, there were no disruptions at the ceremony Thursday. Sen. Chuck Schumer (D-N.Y.) dropped in with a security detail, as the names of graduates were read aloud. He told a tale as he has done countless times at college commencements: the story of how his girlfriend dumped him the summer after his college graduation. He had declined a scholarship to travel “all around the world, all expenses paid, for a whole year” to spend time with her.

“No scholarship. No trip around the world. No girl,” he said.

The crowds cheered for the graduates, who threw their caps into the air as the sun went down close to 9 p.m.

For other students and parents, the day was unbearable. “I feel like it’s unfair. It’s our final day as a class. It’s unfair that we all can’t walk together,” said Franklin Tejada, 18, a senior who was barred from participating.

In an interview Thursday afternoon, Tejada said he did not enter the school grounds during the June 9 incident. He said he helped organize what was supposed to be a prank with balloons, streamers and Silly String.

Lara Bakshi, a Manhattan educational attorney who has represented three of the students before the school district in their efforts to walk in the graduation, said earlier Thursday that the students’ cases were “a lost cause.”

“They feel like this was a very unfair, arbitrary and capricious exercise of the board’s power, and they overstepped their bounds,” Bakshi said. “Today was supposed to be a culmination of the hard work that they have endured and accomplished in four years, and their family was supposed to share in that. Instead, it is a dejecting way for children to go into the future thinking this is the way the world works.”

Students and their parents said that the level of involvement in the prank was varied.

Parents told Newsday that about 70 seniors participated in what was supposed to be a prank in which students would scatter balloons and paper streamers. Students said that six students wore masks and committed the more serious acts of vandalism.

Gladys Santos said she was “really sad and upset” about the decision. Her daughter “all this week, she cried a lot.”

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Santos took her out to dinner in Garden City on Thursday night with family visiting from Puerto Rico and Texas specifically for the graduation. She said her daughter was in the lobby and only placed balloons there during the prank.

“I tried to make a great night for her,” Santos said. “It was supposed to be exceptional, a really good night.”