BEIRUT (AP) — A Syrian war monitor and an opposition paramedics group say an explosion in the rebel-held northwestern city of Idlib has killed at least three people and wounded others.

The Civil Defense, also known as the White Helmets, said Sunday's blast occurred near a mosque killing three people, including a child.

The Britain-based Syrian Observatory for Human Rights said four people were killed, including a child and a foreign fighter whose nationality was not immediately clear.

The Observatory said the blast occurred in al-Qusour neighborhood that is inhabited by many fighters from Uzbekistan and China.

Idlib province is the last major stronghold of insurgents and home to many foreign fighters with al-Qaida linked groups.

A deal between Russia and Turkey last month averted a government offensive on the area.