DAMASCUS (Dispatches) -- 
Syrian authorities are investigating the cause of an explosion that destroyed a weapons depot in the southern Aleppo countryside on Monday, the fifth such explosion in the past three weeks.
The defense ministry under de facto president Abu Muhammad al-Jolani, a former Daesh and Al-Qaeda deputy, is opening an investigation into the cause of the explosion near Al-Eis in southern Aleppo, which injured four people, SANA reported.
More than 10 blasts were reported at the site, which were heard across parts of the western and northern Aleppo countryside.
SANA added that relevant authorities were investigating the causes of explosions at several such weapons depots in recent weeks and that they would take measures to protect personnel and military sites and prevent similar incidents.
The weapons depot that exploded at dawn Monday was the fifth in three weeks.
On September 1, at least five people were killed when munitions exploded while being transferred from a vehicle to a warehouse in the town of Binnish, in the northwestern governorate of Idlib.
A week later, on September 9, at least 14 people were killed and 11 wounded when an explosion ripped through a temporary storage facility for weapons and explosive material in the city of Sarmada in Idlib.
On September 12, an explosion at an ammunition depot in the Al-Dumayr area of the Damascus countryside caused material damage but no casualties.
On Saturday, an explosion struck a weapons cache at a Syrian army position in Ayyash in Dayr al-Zawr governorate, killing 11 military personnel.
Syrian Brig. Gen. Muhammad al-Baqaei discussed several explanations for the recent explosions, including deliberate sabotage, explosives planted at the facilities, or mishandling of remnants of explosives left behind from earlier fighting.
Regarding the Aleppo blast, Baqaei said he was “almost certain that this was a deliberate act of sabotage,” while suggesting that unidentified aircraft could also have targeted the depot, including possibly Israeli aircraft.
On August 18, Israeli warplanes bombed the Abu Duhur military airport in Idlib, claiming that the Turkish military was using the site to build up its forces in Syria. The blast caused material damage to the runway but resulted in no casualties.