The official at the governor's office in Homs province says Thursday's explosion in the village of Jbourin also wounded four people on the bus. He spoke on condition of anonymity in line with regulations.
The village is predominantly Alawite, a minority sect to which President Bashar Assad belongs, but it also has Christians and Sunnis. It was not immediately clear why the bus was targeted.
Syria's civil war, which has left more than 100,000 dead since the crisis erupted in March 2011, has taken increasingly sectarian overtones. Most of the rebels trying to overthrow Assad belong to the majority Sunni sect.
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