CAMBRIDGE - An MIT junior was found dead in his dorm room early Tuesday after inhaling laughing gas, campus officials said.

Richard Guy, 22, of Mission Viejo, Calif., was discovered in his East Campus residence hall at the school shortly after midnight. The physics major was asphyxiated while using a plastic bag to inhale nitrous oxide.

This is the second substance-related death to shock the MIT campus at the start of school in recent years. In September 1997, 18-year-old freshman Scott Krueger died three days after he was found in an alcohol-induced coma on a fraternity floor.

Police were investigating Guy's death as an accident. The medical examiner said Guy died from asphyxiation as a result of nitrous oxide intoxication.

"It's just a shame,'' said Chris Johnson, 19, an MIT sophomore from Columbia, Tenn. "Some of the smartest kids in the world are here. Maybe they think they're too smart to suffer the consequences.''

Used as a recreational drug to get high, nitrous oxide can cause dizziness, light-headedness and euphoria.

Massachusetts Institute of Technology officials were releasing few details.

Classes aren't scheduled to begin at MIT until Sept. 7, but freshmen and some upperclassmen had already moved into their rooms for the start of the academic year. East Campus, where Guy lived, is a dormitory of single and double rooms housing about 400 students.

A small group of students gathered in the courtyard outside the building around 1 a.m. after hearing the news. Tuesday night, a sign outside the dorm read "Press Vultures Go Home,'' and several students declined to speak to reporters.

Students outside MIT's student center said the campus was gradually absorbing the news of another death.

"It's unfortunate but not entirely surprising,'' John Rodriguez, 26, an MIT graduate student from Houston, said Tuesday night outside MIT's student center. "I hope some people will wake up and say, `We've got to think about what we're doing.'''

Pure nitrous oxide dissolves in the bloodstream, pushing oxygen out from the blood into the lungs, depriving the brain and other organs of oxygen. Dentists frequently use it as a painkiller.

In June, a Viera, Fla., man was charged with manslaughter in the death of his girlfriend, who passed out with a plastic bag over her head while sniffing laughing gas.

Krueger's 1997 death prompted MIT to re-examine its alcohol and disciplinary policies. And about a year after the death, the school announced that all freshmen starting in fall 2001 will be required to live in campus dorms and not in fraternities.

The Krueger case also prompted a criminal investigation which resulted in the indictment of the fraternity for manslaughter. The indictment was moot because no one showed up for the arraignment.

Carol Miu, 19, an MIT sophomore from Syosset, N.Y., said she sees the deaths of Krueger and Guy as isolated incidents.

"Most people I know don't drink, especially in fraternities, especially after the Scott Krueger incident,'' she said.