A human rights group says at least 24 people have been killed in a double bomb attack in Syria's Idlib Province.

The Britain-based Syrian Observatory for Human Rights says two explosions occurred on Monday in central Idlib, northwestern Syria.

The group says the first blast was likely caused by an explosive device planted in a vehicle. Another bomb was detonated when ambulances were arriving at the scene.

The 24 fatalities reportedly include four children. Dozens of others were injured.

So far, no one has claimed responsibility for the attack.

Idlib is the last major stronghold of Syria's opposition forces.

An extremist group affiliated with Al-Qaeda has expanded its control in the region, while opposition groups compete with each other.

The government of President Bashar al-Assad has bombarded areas around Idlib, resulting in an increasing number of civilian casualties.

NHK