An MIT sophomore was critically injured in an unexplained fire in her dorm room Monday night.

The student, who was taken to Massachusetts General Hospital, suffered third-degree burns on 55 percent of her body, said Cambridge Fire Department Captain Kenneth Jenness.

An investigation into the cause of the fire is ongoing, Jenness said.

"When the smoke detectors went off in her single room, a neighboring student called campus police and pulled the fire alarm," said MIT Dean of Students and Undergraduate Education Rosalind H. Williams in a news release issued yesterday.

MIT police responded to the fire alarm and arrived at the student's dorm, Random Hall, at 9:15 p.m. Seven MIT police officers were treated for inhaling smoke while rescuing the student and attempting to extinguish the fire, according to the release.

The one-alarm fire was successfully confined to the student's fourth floor single.

The 92 other students living in Random Hall evacuated the building immediately and were able to return after several hours.

The dozen students who live on the fourth floor were allowed to return to their rooms by 2 a.m., only five hours after the fire began, house officials said in yesterday's release.