Last Updated Mar 28, 2013 2:40 PM EDT
DAMASCUS, Syria Mortar shells slammed into a cafeteria at Damascus University on Thursday, killing up to 15 people and wounding 20 in what was the deadliest in a string of such attacks on President Bashar Assad's seat of power, state media and officials said.
Rebels began firing shells at the capital earlier this year, and the strikes have become increasingly common in recent weeks as rebels clash with government troops on the east and south sides of the city.
State-run TV said the casualties occurred when mortar shells struck the cafeteria of the university's architecture department in the central Baramkeh district.
Early reports regarding the number of dead have differed, with the toll being listed variously as 10, 12 and 15 people killed. A Syrian official who spoke to The Associated Press on condition of anonymity because he was not authorized to give official statements said 20 people were wounded in the attack.
There was no immediate claim of responsibility for the attack, which came two days after rebels barraged Damascus with mortar shells that killed at least three people and wounded dozens.
The shelling rarely causes many casualties, but it has shattered the aura of normalcy the regime has tried to cultivate in Damascus. In recent days, rebels have struck deeper than ever into the heart of the city in a new tactic to try and loosen Assad's grip on his main stronghold.
The government blamed "terrorists," the term it uses for rebels fighting to oust Assad, and called the attack as a "barbaric massacre."
Government-run Al-Ikhbariya TV showed footage of plastic tables and chairs turned upside down, shattered glass and pens and books scattered on the floor. Pools of blood were seen on the floor of the open-air cafeteria. The station showed paramedics trying to revive a wounded girl.
The Britain-based Syrian Observatory for Human Rights confirmed the attack, saying many of the wounded were in critical condition.
Syria's crisis began in March 2011 with protests demanding Assad's ouster. Following a harsh government crackdown, the uprising steadily grew more violent until it became a full-fledged civil war. The U.N. says Syria's two-year civil war has killed more than 70,000 people.
The mortar attack at the university occurred as officials denied opposition claims that an Iranian cargo plane allegedly carrying weapons to Assad's regime was hit as it landed at Damascus International Airport.
Al-Arabiya and Al-Jazeera TV quoted activists as saying that the plane was hit Wednesday night and caught fire as it was landing. State-run TV denied the report while the Observatory chief, Rami Abdul-Rahman, said he could not confirm that such an incident happened.
Ghaidaa Abdul-Latif, the general director of the Syrian Arab Airlines, denied in a telephone interview with The AP the occurrence of any incident at the airport. She stressed that all reports about the incident were "absolutely untrue."
Earlier in the day, activists said Syrian rebels attacked army checkpoints in and around a key southern town that is a gateway to Damascus.
The Observatory said rebel attacks were under way in and around Dael in the strategic Daraa province, which borders Jordan. The Local Coordination Committees, another activists group, said regime bombardment of Dael killed at least three people on Thursday.
The Observatory also reported violence in other parts of Syria, including the northern regions of Idlib and Aleppo, and air raids on the suburbs of Damascus.
The fighting comes as Mideast powers opposed to Assad have stepped up weapons supplies to Syrian rebels in coordination with the U.S. in preparation for a push on the Syrian capital, according to officials and military experts who spoke to the AP in Jordan.
In Jordan, the U.N. refugee agency said a riot broke out at a refugee camp for Syrians in the country after some of the refugees were told they could not return home.
Ali Bibi, a U.N. refugee liaison officer in Jordan, said it was unclear how many refugees were involved in Thursday's melee at the Zaatari camp. The riot broke out after some Syrians in the camp tried to board buses to return to their country.
He said Jordanian authorities refused to let the buses head to the border because of ongoing clashes between the rebels and Assad's forces in southern Syria, just across the border from Jordan. Bibi said there were no immediate reports of injuries.
Turkish officials on Thursday denied reports that the country was deporting several hundreds of Syrian refugees for causing disturbances inside a refugee camp near the border. A Foreign Ministry official said, however, that a group of 100 refugees asked to be allowed to leave the camp and to return to Syria on their own free will.
A fire at the camp in the town of Akcakale late Wednesday killed a 7-year-old child and sparked unrest among the refugees.
A camp security official said local authorities identified about 300 people who allegedly caused the disturbance and prepared to deport them. But the move was stopped by government officials, he said. He spoke on condition of anonymity because he was not allowed to discuss the situation in the camp with journalists.
The U.N. refugee agency could not immediately confirm the reports, but said it was concerned by allegations of possible deportations from Akcakale and was seeking further information.
In Israel, the military said it was beefing up medical teams along the border with Syria following several cases of wounded Syrians crossing the frontier to seek medical assistance.
A military official, who spoke on condition of anonymity under military protocol, said on Thursday there have been "numerous incidents" in recent months in which Syrians wounded in the fighting in their country arrived at the frontier for first aid from Israeli medics.
Eleven of them were taken and treated at Israeli hospitals, including one who died from his wounds on Wednesday. Others returned home after their conditions have improved.
The official spoke on condition of anonymity under military protocol. He said the military's focus in the Israeli-held Golan Heights was still on security and defense but that Israel sent extra medical teams to the area realizing more wounded could soon arrive.