BEIRUT: Three massive explosions Tuesday shook the Syrian government’s Hamidieh military base in Idlib province that rebel groups said resulted from a three-month-long tunneling effort to detonate the explosives under army checkpoints.

A local anti-regime media activist group said at least 35 troops and paramilitaries had been killed in the blasts, which were carried out by the Free Syrian Army’s Division 13 and Ahrar al-Sham, a member of the conservative Islamic Front alliance.

The Syrian Observatory for Human Rights, a Britain-based, anti-regime monitoring group, also reported the blasts and said the regime side had suffered “confirmed” casualties, as heavy fighting erupted in the area.

Activist groups posted YouTube videos of the blasts, which targeted checkpoints around Hamidieh, south of the town of Maaret al-Numan.

Fierce fighting was also reported in next-door Hama province, as rebels advanced against government positions near the city of Morek, on the highway linking Aleppo to Hama, anti-regime activists said.

The regime has made repeated attempts to seize Morek throughout the year.

In Aleppo province, the Observatory said rebel groups recovered the corpses of five regime soldiers in the Handarat area, after days of fierce clashes. Rebels also shelled the citadel of Aleppo in the provincial capital with mortar bombs, although no information on regime casualties was available.

Separately, at least 10 soldiers were killed in fighting with ISIS jihadists in the eastern province of Deir al-Zor, which also took the lives of three civilians, the Observatory said.

It said the fighting was in Hawijat Sakr on the Euphrates River, not far from Deir al-Zor military airport, a key remaining post for the Syrian army in the oil-rich province.

ISIS controls most of the province, but parts of the regional capital, Deir al-Zor city, are still in government hands, along with the airport.

Deir al-Zor has been a key target of strikes against ISIS by the U.S.-led coalition fighting the jihadist group in Syria and Iraq.

When the raids began, ISIS withdrew from several positions, and there have been few reports of clashes involving the group in the province since.

Elsewhere, the Observatory reported at least 12 people killed, including three children, in regime airstrikes on the Ain Tarma area outside Damascus.

Ain Tarma is under rebel control and is one of the areas that regime forces have been battling to capture.

Although government forces control Damascus, rebels often fire missiles into the city from several strongholds on its outskirts.

The regime also carried out airstrikes against Arbin, another rebel-held area east of Damascus, the Observatory said.

The strikes killed eight people, although the group said the death toll was likely to rise because several of the wounded were in serious condition.