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A large explosion hit a Syrian government-held coastal town on Thursday, killing at least 10 people and wounding dozens, according to Syria's state TV. The attack was a major blow to the nearly week-old and already shaky cease-fire brokered by Russia and Turkey.

First videos that emerged from the scene in the town of Jableh show charred cars, some turned upside down, and extensive damage to shops lining a commercial street crowded with onlookers. Images aired on state al-Ikhbariyah TV show pools of blood covering the asphalt as fire engines were scrambling to put out small fires, apparently caused by the explosion.

Qusay al-Khalil, the head of the local hospital, said the blast also severely wounded at least 30 people. "The explosion rocked the town," he told state TV, adding that it prompted a state alert at his hospital.

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The Britain-based Syrian Observatory for Human Rights, which tracks the civil war, put the death toll at 15. The monitoring group relies on a network of activists on the ground in Syria.

No group immediately claimed responsibility for the bombing in Jableh, which lies in the coastal Latakia province, the heartland of Syria's Alawites, a Shiite offshoot to which President Bashar Assad's family also belongs.

The Islamic State group and the al-Qaida-linked Fatah al-Sham Front are not part of the broad truce that the Syrian government and the opposition agreed on last week.

The cease-fire, which came into effect on Dec. 30, has largely held, except for intense fighting in the Barada Valley outside Damascus, a major source of water for the capital. Both the government and the rebels have accused the other side of violating the truce.

In comments published Wednesday, Syria's al-Qaida-linked group said the cease-fire is "humiliating" and that those who agreed to it made a "big mistake." The Fatah al-Sham Front spokesman Hossam al-Shafei also said major battlefield victories are necessary for a political solution to be reached.

Although explosions are rare in the government-controlled Latakia, Jableh was rocked in May last year by a string of blasts that first hit in a crowded bus station, then outside a hospital receiving the wounded, killing a total of about 120 people. Those attacks, which also came amid another tested cease-fire, were claimed by the Islamic State group.

Police chief of Latakia province Yasser al-Shariti told state TV the explosion hit during rush hour when government employees and students were crowding one of the town's main streets, located near a sports stadium. Others said the area was packed with shoppers, many coming from or going to a popular vegetable market nearby. Jableh has also been home to thousands of internally displaced Syrians who have sought the relative calm of the government-controlled town.

Under the new cease-fire agreement, Russia and Iran are tasked with ensuring compliance by the Syrian government and its allies, while Turkey is serving as a guarantor for the rebels. On Wednesday, Turkey called on Iran to rein in the pro-government forces. Tehran countered by accusing the opposition of dozens of violations and called Turkey's comments "unconstructive."

The government in Damascus says the truce does not apply in the Barada Valley because of the presence of al-Qaida-linked fighters. But activists and rebel groups have challenged the government claim, with some arguing the militants don't operate in the area. The rebels have said all areas not ruled by IS are covered under the agreement.

The truce was meant to pave way for peace negotiations planned for later this month in Astana, the capital of Kazakhstan, but nearly a dozen rebel groups announced on Monday they were suspending talks about the negotiations.

On Thursday, senior Iranian lawmaker Alaeddin Boroujaerdi, on a visit to Damascus, stressed that the al-Qaida-linked group and IS are not part of the agreement and that "matters are settled with them on the battlefield." Boroujaerdi, who is in charge of foreign policy and national security portfolios in Iran's Shura Council, said that for any truce to hold, all militant groups must leave Syria.

The presence of al-Qaida-linked militants, who fight alongside other rebel factions and have been credited with some of their biggest victories, has undermined past truce attempts. The Fatah al-Sham Front, formerly known as the Nusra Front, announced last year that it had severed tied with al-Qaida, but is still widely believed to be linked to the global terror network.

Fatah al-Sham spokesman al-Shafei said in an interview published late Wednesday by Al-Jazeera Net that the current truce only protects Assad and allied Iranian-backed militias.

"The people of (Syria) didn't offer all these sacrifices to be handed this humiliating agreement," he was quoted as saying. The Syrian rebellion "today needs someone to ... strengthen its political position by battlefield achievements," he said.

The rebels demand that any future solution for Syria include Assad's exit from power.

But Boroujaerdi said peace talks should not put any conditions on the Syrian leadership. He also chastised Turkey for sending troops into northern Syria as one in a series of Ankara's policy "mistakes." He added that any troops in Syria without the government's approval or permission should leave "immediately."