UNITED NATIONS, Aug. 26 (Xinhua) -- Fifteen people were killed over the weekend in attacks in northwest Syria, a UN spokesman said on Monday.

Hostilities continued to impact civilians in the northwest part of the country, across Idlib, northern Hama and western Aleppo governorates," said Stephane Dujarric, spokesman for UN Secretary-General Antonio Guterres.

According to the United Nations Office for the Coordination of Humanitarian Affairs, "fifteen people, including four children, were reportedly killed," Dujarric said.

"In Idlib alone, displaced people have sought shelter in more than 100 schools. Camps for the displaced people are already overcrowded, with hundreds of thousands of people forced to stay out in the open air, outside camps and reception centers," he said.

The spokesman said that since the start of hostilities in that area nearly four months ago, there have been nearly 575,000 individual displacement movements.

Many people have been displaced up to five times, while some have been displaced up to 10 times.

With the new school year about to begin, access to education will be compromised for many children, he said.

He urged all parties to the conflict to de-escalate the situation.