Syrian air defenses have thwarted what the state TV called "hostile" fires in the northwestern city of Masyaf in the Arab country's Hama governorate.
According to government-affiliated sources, explosions heard in Masyaf were a result of shells launched by anti-Assad militants in the western countryside of Hama.
The city of Masyaf is known to be one of the places where the Russian air defense system S-300 is deployed.
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The explosions came a few hours after a cargo train carrying phosphate through central Syria was targeted and derailed by a "terrorist" attack, the Syrian transport ministry announced.
The train's crew suffered "various injuries" when it came off the tracks in Homs province, spilling the loads from two cars and starting a fire, it said.
A bomb placed by "unknown people" on a stretch of track east of Palmyra had exploded as the train passed, the UK-based Syrian Observatory for Human Rights reported.
The train was put "entirely out of service" as a result of the incident, the war monitor added.
Meanwhile, the Syrian army's airstrikes against militants' positions in Idlib region killed at least 18 people in the northwestern region, the Observatory said.
Idlib is a final flash point and the last bastion for foreign-backed militants.
The Syrian army warned civilians to leave Idlib before the campaign began to flush terrorists out of the region.
Syria has been gripped by foreign-backed militancy since March 2011. The Syrian government says the Israeli regime and its Western and regional allies are aiding Takfiri terrorist groups that are wreaking havoc in the country.
The government forces have already managed to undo militant gains across the country and bring back almost all of the Syrian soil under the government control.