Student supporters of the government and the thugs known in Arabic as shabiha helped the police and soldiers put down the demonstration, activists said.

It was fellow students and shabiha who threw Samer Qawass, an 18-year-old Islamic studies student from the city of Idlib, out of the fifth-floor window in Building 17, killing him, said Thaer al-Ahmad, a law student and activist who said he had participated in the demonstration. A statement from the Local Coordination Committees, an opposition group, and an interview with another activist echoed his description. The second activist said that Mr. Qawass died instantly from the fall. Student housing, known as University City, consists of 20 dormitories.

Demonstrations tend to start inside the dorms, but if they get large enough they spill out onto the campus, Mr. Ahmad and other students said. “We always demonstrate but this time it was different; the storming of the dormitory was fierce,” he said. The protest was called, he said, to observe the anniversary of the first anti-Assad demonstration there. (There were also reports that the protest and the response were bolder than usual because United Nations cease-fire monitors were nearby, but a spokesman denied that they had visited Aleppo.)

The security forces raided rooms, breaking windows, throwing furniture outside and eventually opening fire, Mr. Ahmad said, causing panic among the students as even the female students were forcibly ejected from their rooms. Videos online appeared to corroborate his account, showing dormitory windows smashed with a fire still raging on one floor, mattresses on the ground outside and several rooms ransacked.

The Syrian government has barred most independent journalists from the country, so the opposition accounts and videos are difficult to authenticate. As of late Thursday there was no account of the protest or suppression of it from Syria’s state-run news media. The protest started late Wednesday and raged long into the night. One amateur video showed dozens of security officers, truncheons raised, running on the campus in daylight. In another one, shot after dark, security officers can be seen running from one high-rise dormitory to the next under the yellow of campus lights, with the staccato of gunfire erupting in the background.

The death toll was at least 4 students, with more than 20 wounded, 3 of them seriously, according to several opposition statements, and more than 200 students were arrested. The Local Coordination Committees put the number killed at six. Later the security forces walked around the campus with loudspeakers demanding that all the students leave the dormitories, the opposition statements said.

Also on Thursday, Maj. Gen. Robert Mood, the Norwegian head of the unarmed United Nations cease-fire mission, visited Homs and Hama, telling reporters that the observers were having a “calming effect,” according to news service reports, adding that there remained “a good chance and opportunity” to end the violence.

There are now 50 observers in Syria out of an expected total of 300 by the end of May, he said. A video posted online, said to have been filmed during an encounter with some men in military uniforms described as defecting officers, showed General Mood telling them that while he had sympathy for the change that Syrians were seeking, he wanted to uphold his United Nations mandate for a cease-fire.