An 18-year-old Gallaudet University student was arrested yesterday in the beating death of classmate Eric Franklin Plunkett, whose body was found in his dormitory room on Thursday.

Thomas Minch, of Greenland, N.H., was arrested at 5:30 p.m. at 5th District headquarters and charged with second-degree murder, police said.

The two young men--both freshmen at the university--had a dispute that erupted into a physical altercation, ending with Plunkett's death, police said. They would not say what the dispute was about, but said they think a chair in the room may have been used to kill Plunkett.

About two dozen Gallaudet students waited anxiously outside the 5th District headquarters last night and some broke into tears when Minch's arrest was announced.

Plunkett, who suffered from cerebral palsy, was found dead Thursday in his room at Gallaudet, a premier university for the deaf and the hard-of-hearing. The D.C. medical examiner's office ruled the death a homicide.

Fifth District Cmdr. Jennifer Greene released few new details about the slaying last night.

Plunkett recently joined the Lambda Society at Gallaudet University, a student-run campus club for gay and straight students, whose members have complained of some anti-gay hostility on campus.

Word of the arrest spread quickly on campus. "I still can't believe it's him," said freshman Chris Adams. "I'm still in big shock."

Students who knew Minch said he lived in Krug Hall, the dormitory opposite Cogswell Hall, where Plunkett had lived alone, and that the two young men were close friends. Shoshannah Stern, a junior, said the two students' families sat together during the August ceremonies held on campus for new students. "He said Eric was one of his closest friends," Stern wrote in a reporter's notebook in response to questions.

Many Gallaudet students, including Stern, attended a 1996 youth camp for the deaf with Minch in Stayton, Ore. Plunkett also had ties to Oregon; he attended a school for the deaf there before moving to Minnesota and attending the Minnesota State Academy for the Deaf.

Minch was described by students as polite and sensitive. "I saw him when he enrolled and he was very gregarious and friendly," Stern wrote.

Late into the night, detectives continued to question Minch, with the help of a sign-language interpreter, Greene said.

Minch was first brought to the precinct headquarters and questioned yesterday. He called his parents last night to tell them of his arrest, she said.

Outside the headquarters, students said they were shocked and broke into tears when Sgt. Joe Gentile, a police spokesman, handed out news releases to reporters and students just before a news conference was held. "I just couldn't believe it," said Rebecca Goldenbaum, a junior, who cried and hugged friends. "I was in complete shock. I kept thinking, 'No, no, this can't be right.' I just couldn't believe it was him."

Greene said that based on preliminary forensic evidence, the chair is most likely what was used in the killing. Further tests are being conducted.

Greene said police zeroed in on Minch after numerous interviews with students and calls from tipsters.

Gallaudet University officials also expressed shock that one of their students had been arrested. "We're relieved that someone has been apprehended on the one hand," university spokeswoman Mercy Coogan said. "But on the other hand, we're devastated that it's one of our students."

In New Hampshire, those who knew Minch said they were shocked as well. "He was very well respected," said Richard Gremlitz, the principal of Portsmouth High School. Minch was one of 225 students who graduated from the school in the spring.

"He was in a number of our theater productions," Gremlitz said. "He had an actor on the sidelines filling in his voice while he played a part in 'Bye Bye Birdie.' "

Minch was honored as the outstanding graduate in the technical arts and theater for his work on both sides of the floodlights, Gremlitz said.

Pamela Pritzker, who said she was a close friend of Minch's since kindergarten, said she had corresponded with him by e-mail Monday night.

Pritzker, a freshman at Northeastern University in Boston who is studying American sign language, said she asked Minch about Plunkett's slaying. "I said, 'Are you okay?' He said, 'Yeah,' and he sort of left it alone." She said that Minch said the person who died was a good friend and that he had attended a candlelight vigil for him.

At a meeting at the university before the arrest was announced, students saw a letter to them from Plunkett's mother, Kathleen Cornils, of Burnsville, Minn.

"While we are all struggling to understand why this terrible tragedy happened, we are receiving support from many, many people, including our church, our many friends and the Gallaudet community," the letter read.

Staff writers Petula Dvorak, Allan Lengel and David Fahrenthold and Metro research editor Margot Williams contributed to this report.