Newark, N.J. ? Nearly seven years after a dormitory fire killed three students at Seton Hall University, two former roommates pleaded guilty Wednesday to arson, admitting for the first time that they set a banner ablaze in a prank that tragically got out of hand.

Joseph T. LePore and Sean Ryan, both 26, struck a deal with prosecutors as they were about to go on trial on murder charges. They will get no more than five years in prison, compared with 30 years or more if they had been convicted of murder.

Prosecutors said LePore and Ryan, up late after celebrating a victory by the basketball team, set the banner on fire in a third-floor lounge around 4:30 a.m. on Jan. 19, 2000, and the flames spread to a couch. The fire was largely confined to the lounge, but choking smoke spread throughout the six-story dorm.

Eighteen-year-old freshmen Frank Caltabilota, John Giunta and Aaron Karol were overcome by smoke and died. Dozens of others were injured, some of them seriously burned.

“I did not intend to harm or injure anyone. It was a prank that got out of hand,” the two young men, lifelong friends from Florham Park, said in matching statements.

They also pleaded guilty to witness tampering for telling some friends to lie to authorities.

Karol’s father, Joseph Karol, thanked prosecutors for their dedication but said little else as he left the courthouse after the pleas. “I will tell you that I’ll have plenty to say at sentencing,” Karol said.

The defendants did not speak to reporters. Their attorneys said that the men felt terrible about what happened but that it was not the time to speak or express remorse.

The fire led New Jersey to enact the nation’s first law requiring sprinklers in dormitories at colleges and boarding schools.

The blaze was quickly determined to be arson. But the unsolved case haunted the Roman Catholic university and the criminal justice system for years. It was not until 2003 that the defendants were charged.

Through their lawyers, the defendants had for years denied their involvement in the fire at the school in South Orange. The defense had decried the circumstantial case against the men, including information provided by a former mob hit man that helped prosecutors get a warrant to eavesdrop on LePore’s family.

The men’s lawyers said the deal was appropriate in part because the school did not have adequate systems to prevent the blaze from spreading.