Mortar rounds slammed into an elementary school on the outskirts of the Syrian capital Tuesday, killing at least 15 people, according to state media and opposition activists.

The attack occurred at a school in the Wafideen refugee camp, which is about 10 miles north of Damascus and houses Syrians displaced from the Golan Heights in 1967. Syrian state television said 14 students and a teacher were killed and 18 people were injured, while the Local Coordination Committees opposition network said 30 students were killed.

The Syrian Arab News Agency blamed the attack on “terrorists,” the term commonly used by official media to refer to rebel fighters. The Local Coordination Committees attributed it to the government.

Activists also said Tuesday that at least 25 people were killed in a government attack in Bahdaliya, a neighborhood south of Damascus close to the capital’s airport highway, which has been the scene of intense fighting between rebels and government forces in recent days.

The Syrian military has repeatedly bombed and shelled the area as opposition forces have pushed to take control of the highway and perhaps the airport.

Interactive: Recent events in Syria

A gruesome video posted online Tuesday reportedly showed the victims of the attack, most of whom appeared to be young men of fighting age. Because of the Syrian government’s restrictions on media access, the authenticity of the video could not be confirmed.

According to opposition groups, the Syrian military has often targeted civilian areas since the start of the uprising, which the groups say has left more than 40,000 dead.

Across the border in Lebanon, clashes broke out between Sunni and Alawite residents in the northern city of Tripoli, leaving at least two people wounded, local media reported. Gunmen also opened fire on army vehicles deployed in the city to stop the clashes.

Many Sunnis in the city support the Syrian opposition, which is led primarily by Sunnis, while the Alawite residents largely support the government of President Bashar al-Assad.

Tensions have been running high since 21 Lebanese fighters from Tripoli were killed in an ambush by the Syrian army in the Syrian town of Tel Kalakh on Friday.

The Syrian ambassador to Lebanon, Ali Abdel-Karim Ali, said in a statement Tuesday that the Syrian government was considering sending the bodies of the fighters back after a request by the Lebanese government.

Ahmed Ramadan contributed to this report.

A look at the Syrian uprising nearly two years later. Thousands of Syrians have died and President Bashar al-Assad remains in power, despite numerous calls by the international community for him to step down.