(CNN) At least 28 people were killed when warplanes struck a refugee camp Thursday in Syria, the monitoring group Syrian Observatory for Human Rights reported, with many of the dead women and children.

Rami Abdul Rahman, director of the London-based group, told CNN it was not immediately clear whether Syrian or Russian planes conducted the airstrike.

The planes attacked the Kamuna camp next to Sarmada village in the northern countryside of Idlib province on the border with Turkey, according to the observatory.

Majd Khalaf, a civil defense officer in Syria, said the number of casualties may go higher because so many people were injured. He said two jet fighters struck the camp, according to eyewitnesses the civil defense team interviewed.

Video showed tents burning while men with firehoses tried to put out blazes. Men covered and carried away bodies, and women and children lying in a truck bed wailed in anguish before a vehicle drove them away.

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