Syrian activists say government forces have raided university residence halls and killed at least four people in Aleppo, as United Nations monitors continue their push to end violence that has increased during a deteriorating cease-fire.

Rights groups and activists said Thursday that forces used tear gas and live ammunition in the overnight raids at Aleppo University. Activists say forces detained at least 200 students as they stormed the campus following an anti-government protest.

The French news agency says forces also carried out at least two raids in Damascus province on Thursday.

Several dozen U.N. monitors visited areas including the flashpoint Homs and Hama regions on Thursday. They are assessing the government and rebels' compliance with a cease-fire and peace plan brokered by international envoy Kofi Annan.

VOA's Middle East correspondent Elizabeth Arrott toured Hama and Homs with U.N. observers on Thursday and saw scenes of widespread destruction.

“There is a corridor north of Damascus between Homs and Hama that has been very, very hard hit by the fighting and the unrest. And it's very clear. For example, in one town, the outskirts of Arasa which is still very much a flashpoint town, on the northern side of the town, every house has holes blasted through them. In Homs, you see holes in the houses, windows blasted out, widespread destruction in the whole area.”

The Norwegian officer who heads the U.N. mission, Major-General Robert Mood, told reporters in Hama that he hopes the observers' presence will have a “calming effect” to end the violence and put negotiations on a political track.

The observers had reported earlier that the Syrian military had heavy weapons stationed in some cities. The U.N. team says both the government and opposition have violated terms of the peace plan.

The United Nations estimates at least 9,000 people have been killed since President Bashar al-Assad began cracking down on an uprising against him in March of last year.