The UN admitted a shaky three-week-old truce in Syria is not holding but said the number of observers would be doubled within days, as violence erupted Thursday near Damascus and the northern city of Aleppo. Aleppo University announced it was suspending classes after pro-government forces killed four students and arrested more than 200 in a campus raid during anti-regime protests. In a message posted on its website, the northern city's university told students that classes were suspended until final exams on May 13. “Students were barred from entering the campus and were told that the university dorms were shut down until further notice,” Mohammed Al-Halabi, an activist on the ground, said via Skype. Security forces had raided the dormitories Thursday morning and had thrown out students and their belongings, he said, adding that some of the rooms were torched. The closure came after troops and armed supporters stormed an anti-regime protest on campus overnight, killing four students and arresting more than 200, said the Syrian Observatory for Human Rights. The Britain-based watchdog also reported that 28 students were wounded, three of them critically. In a video posted by activists on YouTube, heavy gunfire and screams are heard while dozens of men, identified as members of the security and intelligence services, are seen entering the campus. The video could not be authenticated as Syrian authorities have restricted access to foreign media. Several protests in solidarity with the Aleppo students broke out Thursday in various universities across the country, activists said. The Syrian Observatory said security forces early Thursday launched raids in the town of Douma and farmlands outside Harasta, both in Damascus province. Human Rights Watch accused the regime of committing atrocities in the eastern province of Idlib shortly before the truce took effect. “Syrian tanks and helicopters attacked one town in Idlib after another,” Anna Neistat, associate director for programs and emergencies at HRW, said in a statement. A top US Treasury Department anti-terror official, Daniel Glaser, is meanwhile embarking on a tour of Saudi Arabia, Kuwait, Qatar, Israel and the United Arab Emirates to discuss sanctions against Syria as well as Iran. Glaser will “highlight the need for governments and financial sectors to remain vigilant against attempts by the Syrian and Iranian regimes to evade multilateral sanctions,” the Treasury Department said.