A new wave of airstrikes targeting the Syrian city of Raqqa, the headquarters of ISIS (also known as Daesh) and the focus of an international military campaign, killed at least eight people, including five children, Syrian opposition groups said Friday.

It wasn’t immediately clear who carried out the latest airstrikes.

A Raqqa-based activist group that reports on ISIS, known as Raqqa is Being Slaughtered Silently, said Friday that most of the casualties in the latest aerial bombardment occurred when warplanes targeted the city’s Heten School. The school, like others in Raqqa, has been taken over by ISIS.

The Syrian Observatory for Human Rights put the death toll at 12, including the five children. Conflicting casualty figures are common in the chaos of Syria’s civil war, now in its fifth year.

An ISIS-affiliated agency, Aamaq, published a video purporting to show nighttime explosions that lit up the Raqqa sky. The video showed a building and several cars on fire, and a man crouching over the bodies of five children. The agency claimed the casualties and destruction were caused by Russian airstrikes that targeted civilian areas.

Meanwhile, warplanes believed to be Russian carried out several airstrikes on a Syrian town near the Turkish border Friday, the Syrian Observatory for Human Rights said, one of several reported close to the boundary this week. The bombardments came days after Turkey shot down a Russian fighter jet it said had entered its air space.

Three airstrikes hit the town of Azaz, about 5 kilometers from the Turkish border in northern Aleppo province, killing an estimated five people including a child, the Observatory said.

The Observatory also reported heavy clashes were raging Friday in Jabal al-Nawbeh and several other areas in northern Latakia province between the Syrian regime army, backed by allied forces, and rebel factions, including the Nusra Front. Casualties from both sides were reported.

Regime airstrikes, meanwhile, hit the city of Al-Qaryatayn, which ISIS captured earlier this year, in Homs province, as well as the road linking the Al-Houla region and the town of Al-Ghajar north of the province, the Observatory said.

Also Friday, the Syrian army repelled an attack by ISIS on the Deir al-Zor axes and in the direction of the city’s military airport, killing a number of militants, according to Hezbollah’s Media War Center.

In other developments, a Reuters data analysis showed that Russian airstrikes in northwest Syria have heavily targeted ethnic Turkmen areas. The data analysis helps explain rising tensions between Moscow and Ankara in the weeks before Turkey shot down the Russian jet.

Long before the incident, Turkey had condemned Russia’s bombing of towns and villages in the north of Syria’s western Latakia province, areas it says belong to Syrian Turkmen, who are Syrians of Turkish descent.

Russian Defense Ministry data, collated by Reuters, shows the bombing raids have struck at least 17 named locations in Turkmen areas since President Vladimir Putin ordered them to begin on Sept. 30.

Russian missiles have destroyed ammunition bunkers, command points and a suicide bomb factory in towns including Salma, Ghmam and Kesladshuq to the west of Syria’s Alawite mountains, according to the data, an area humanitarian groups say is ethnically Turkmen.

Salma, which has a majority Turkmen population, has been bombed on at least eight occasions and has found itself at the center of some of the most geographically concentrated strikes.

A Syrian Kurdish leader said Friday Ankara had shot down the Russian bomber because the groups it backed were losing territory.

“We are extremely worried that the anti-ISIS coalition is being weakened by these bombardments,” a senior Turkish official said.