A university student said troops also shot at the hospital where the wounded were taken, causing an unknown number of casualties, CNN reported.
The activists said another 200 students were arrested.
The reported attacks came despite presence of U.N. monitors, who have reported cease-fire violations by the government and the opposition since the shaky truce was implemented three weeks ago.
U.N. peacekeeping chief Herve Ladsous said 24 unarmed military observers are in Syria. The number is expected to increase to 300 by the end of the month.
The cease-fire, in effect since April 12, is part of a six-point peace plan negotiated by U.N.-Arab League envoy Kofi Annan. His plan includes allowing humanitarian organizations access to the population, releasing detainees, initiating a political dialogue, and withdrawal of government troops from city centers, which the United Nations says the government hasn't met.
"So far, the Syrian regime has taken, really, almost no steps toward fulfilling the core commitments of the Annan proposal," U.S. State Department spokesman Mark Toner said.
Syrian officials said Wednesday they were committed to the peace plan.
"We are waiting for Mr. Annan to take tangible steps toward the armed terrorist groups and take commitments from the states which support and sponsor them to halt violence in Syria," the state-run Syrian Arab News Agency quoted Information Minister Adnan Mahmoud as saying.
Syria's protests began in March 2011 as peaceful demonstrations against the regime of President Bashar Assad, who responded with a brutal crackdown that has left thousands dead and prompted some military defectors to fight against regime troops.
The United Nations estimates that at least 9,000 people have died. Opposition groups said the death toll is greater than 11,000.
The Syrian government has blamed the violence on unnamed terrorist groups.
SANA reported armed terrorists assassinated the son of the Syrian Social Nationalist Party leader and a friend in Homs. Sources told the state-run news agency that terrorists fired on the two with machine guns.
SANA also reported three warrant officers were killed Wednesday.
The news agency said two bodies were recovered near a school in Deir Ezzor showed signs of torture. Government officials said the two people were kidnapped Tuesday by armed terrorists.