Last Updated 2:14 p.m. ET
BEIRUT A Syrian Education Ministry official says a mortar that hit a ninth-grade classroom in the Damascus suburbs has left 13 students and one teacher dead.
Earlier, state media gave a death toll of 29 students and a teacher. The government-run news agency SANA blamed the attack on terrorists, the term used by the government to refer to rebels fighting against the Bashar Assad regime.
The mortar hit the al-Batiha school in al-Wafideen camp, about 25 kilometers (15 miles) northeast of Damascus, according to SANA. The camp houses 25,000 people displaced from the Golan Heights since the 1967 war between Syria and Israel.
"It's a terrorist attack on educational institutions and on students," Hassan Mohsen, the director of Quneitra Education Department, told The Associated Press.
Further details were not immediately released.
The violence comes as Syrian forces fired artillery at rebel targets in and around the capital and the international community grew increasingly alarmed about the regime's chemical weapons stocks.
Syrian rebels have made gains in recent weeks, overrunning military bases and bringing the fight to Damascus. Since Thursday, the capital has seen some of the heaviest fighting in more than four months, killing scores of people, forcing international flights to turn back or cancel flights and prompting the United Nations to withdraw most of its international staff.
"The push to take Damascus is a real one, and intense pressure to take control of the city is part of a major strategic shift by the rebel commanders' strategy," said Mustafa Alani, a Middle East analyst from the Geneva-based Gulf Research Center. "They have realized that without bringing the fight to Damascus, the regime will not collapse."
U.S. intelligence has detected signs the regime was moving chemical weapons components around within several sites in recent days, according to a senior U.S. defense official and two U.S. officials. The activities involved movement within the sites, rather than the transfer of components in or out of various sites, two of the officials said.
But this type of activity had not been detected before and one of the U.S. officials said it bears further scrutiny.
NATO Secretary-General Anders Fogh Rasmussen warned Tuesday that "if anybody uses chemical weapons, I would expect an immediate reaction from the international community."
His comments echoed a warning on Monday from President Barack Obama that there would be consequences if Assad made the "tragic mistake" of deploying chemical weapons.
"Syrian stockpiles of chemical weapons are a matter of great concern," Fogh Rasmussen said as he arrived in Brussels.
Syria is believed to have hundreds, if not thousands, of tons of chemical agents, including mustard gas, a blistering agent, and the more lethal nerve agents sarin and VX, experts say.
Syria is party to the 1925 Geneva Protocol banning chemical weapons in war.
In July, Syria threatened to unleash its chemical and biological weapons in case of a foreign attack. The statement was Syria's first-ever acknowledgement that the country possesses weapons of mass destruction.
But the regime quickly tried to clarify its comments, saying "all of these types of weapons IF ANY are in storage and under security." That appeared to be an attempt to return to the regime's position of neither confirming nor denying whether it possessed non-conventional weapons.
NATO foreign ministers are expected Tuesday to approve member Turkey's request for Patriot anti-missile systems to bolster its defense against strikes from neighboring Syria.
Ankara, which has firmly backed the Syrian opposition, wants the Patriots to defend against possible retaliatory attacks by Syrian missiles carrying chemical warheads.