Syrian security men and students wielding knives attacked a protest march at Aleppo University on Thursday, activists said, killing four and rounding up dozens of demonstrators who were demanding President Bashar al-Assad step down.
In an unusually bloody incident for Syria's hitherto fairly peaceful commercial hub and second city, video posted on the Internet showed young people chanting slogans against the ruling family and being drowned out by gunfire. Activists posted images of a bloodied corpse and what they said was a burning dormitory.
A British-based opposition group, the Syrian Observatory for Human Rights, said at least four were killed and some 28 other students were wounded, three critically. Some 200 were arrested in the latest violence to breached a three-week-old U.N. truce.
Knife-wielding youths had joined the security forces in the attack on fellow students on the Aleppo campus, the group said, adding that teargas had been fired on what started as the latest of an almost daily series of peaceful protests by the students.
"Freedom forever in spite of you, Assad!" chanted the young demonstrators in a video shot in early morning twilight.
There was no comment from officials and it was not possible to verify the account from the northern city whose relatively prosperous, business-oriented population has been slow to join the 14-month-old revolt against the Assad's four-decade rule.
Syria's middle classes, and substantial religious and ethnic minorities, are fearful that an uprising dominated by Sunni Muslims, who form 80 percent of the population, against an elite around Assad, which is drawn largely from his Alawite minority, could descend into the kind of sectarian and ethnic bloodbath they have watched destroy neighbouring Iraq over recent years.
From Aleppo, anti-Assad activists uploaded a picture of one young man who they said was killed, his shirt drenched in blood, and a video of a burning residence block, its windows shattered. Dormitory hallways appeared to have been smashed up and men were dragging furniture outside as students screamed.
The violence was one of many breaches of the three-week-old ceasefire in Syria, where 31 United Nations observers are touring to monitor the truce between state forces and rebels. Around 300 are expected to be deployed by the end of May.
The deal brokered by former U.N. Secretary General Kofi Annan has led to a small reduction in the daily carnage, mostly in cities were monitors are deployed permanently.
The head of the monitoring mission, Major General Robert Mood from Norway, told reporters during a trip to Hama on Thursday that observers were having a "calming affect" and that state forces appeared willing to cooperate with the truce.
"There have been steps taken by the government forces on the ground that indicate a better willingness to live up to the commitments made in the agreement," he said, giving no details.
But clashes have continued, with rebel fighters killing 15 members of the security forces, including two colonels, in a rural part of Aleppo province on Wednesday.
Security forces struck in other parts of the country, too, activists said. They fired mortars at a village in central Homs province and killed six people when they fired on villages in northern Idlib province.
While the city of Aleppo itself has rarely seen clashes, there has been a string of assassinations there, apparently by rebels. The Observatory reported the killing overnight of Ismail Haidar, son of the head of a pro-Assad political party.
Videos and activist accounts, however, are hard to verify conclusively because the government restricts media access.
On Thursday afternoon, protests again erupted at Aleppo University to denounce the overnight assault.
"It is hard to get any information from the students right now. The situation is tense. Security forces are surrounding the campus," said an activist in the city called Mustafa.
While most opposition areas in Syria have been overtaken by an armed revolt against Assad, peaceful anti-Assad protests had been staged almost daily at the university in Aleppo.
It is hard to assess if those protests reflect widespread sentiment among the younger generation native to the city or whether students living there who hail from rebellious hotspots like Idlib and Deraa might be taking a lead in Aleppo.
Syria's uprising began in March 2011 with peaceful demonstrations inspired by a wave of Arab revolts against long-ruling autocratic leaders, but it has become increasingly militarised in response to Assad's violent crackdown.
The UN says more than 9,000 people have died in the crackdown, while the Syrian government says it has lost at least 2,600 of its forces to "foreign-backed terrorists".
The Observatory cited student activists saying security forces ordered students out of dormitories, from where protests had been launched, and had shut the university until May 12.
Despite the turmoil, Syria plans to hold a parliamentary election on Monday under a new constitution which has allowed the creation of new political parities and formally ended decades of monopoly by Assad's ruling Baath Party.
Authorities say the election is part of a reform process, but most of the opposition dismisses it as a sham. (Additional reporting by Mariam Karouny in Damascus; Editing by Alastair Macdonald)