According to the SANA news agency, the device was placed on a motorbike parked near the school.
Syria has been engulfed in a civil war since 2011, with government forces fighting multiple opposition factions and terrorist groups.
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Previous month, nine people were killed and 28 others injured after two car bombs exploded in Syria's northwestern province of Idlib, which is one of four de-escalation zones created after relevant agreements were reached by Iran, Russia, and Turkey during the Astana reconciliation talks last year.