A tense calm has taken hold of the town of Jisr al-Shoghur in northwestern Idlib province after days of bombing and shelling by forces loyal to the government of President Bashar al-Assad.

Residents on Wednesday reported that the shelling and air raids had stopped but a number of reconnaissance drones were flying above the town and surrounding areas.

On Tuesday, Russian and Syrian jets bombed the town and its outskirts, killing 10 civilians and injuring 20 others, Abu al-Fadl Ahmad, a member of the White Helmets, a civil defence organisation, told Al Jazeera.

Among the victims were five children from the same family, Ahmad reported.

Al Jazeera was unable to independently verify the stated toll.

The bombardment campaign sent much of the local population fleeing towards the border with Turkey, said Ahmad, while a number of people with serious injuries were also transported across the border for treatment.

{articleGUID}

The bombings also targeted branches of the White Helmets in the area which did not result in any injuries among its members, he added.

The Syrian army, aided by Russia, has been preparing for an offensive on the last major stronghold of the Syrian opposition, which some fear will start after an upcoming Tehran summit between Turkey, Russia and Iran on September 7.

In remarks published by Turkish media on Wednesday, Turkey’s President Recep Tayyip Erdogan warned that dropping bombs and firing missiles on Idlib could cause a “massacre”.

“God forbid, a serious massacre could take place if there is a rain of missiles there,” Erdogan told journalists on his plane after an official visit to the Central Asian state of Kyrgyzstan, media reports said.

Russian officials have justified the planned military operation in Idlib with the presence of Jabhat al-Nusra (now known as Hay’et Tahrir al-Sham or HTS), an armed group formerly affiliated with al-Qaeda.

On Tuesday, Russian Foreign Minister Sergey Lavrov said that Damascus would have become “the capital of the ISIL caliphate” if Russia hadn’t intervened.

“Idlib is the last remaining de-escalation zone where a few tens of thousands of terrorists are concentrated, headed mainly by Jabhat al-Nusra,” he said on a political talk show on the state-owned First Channel. “One of the main element of the de-escalation agreements was the commitment to pull out the moderate armed opposition from the territories controlled by terrorists, so they face what they deserve.”

Lavrov suggested that Russia’s “partners, including the Americans” did not fulfil commitments to separate the moderate Syrian opposition from “terrorists”.

Over the past several months, the Turkish authorities engaged in unsuccessful efforts to dissolve the HTS. On August 31, Turkey designated HTS a terrorist organisation.

‘Every inch’

Assad has sworn to recapture “every inch” of Syria and has made big gains against rebels since Russia joined his war effort three years ago.

His forces have been amassing around Idlib, presumably in preparation for the assault to seize the bastion of the rebel groups who have been trying to overthrow Assad since the start of the war in 2011.

Turkey, whose army controls a string of military posts around Idlib, has for weeks been engaged in diplomatic efforts to prevent a Syrian government attack on Idlib.

In Geneva, UN envoy Staffan de Mistura on Tuesday called on the leaders of Russia and Turkey to draw up a solution in the coming days to prevent a major battle for Idlib.

“A telephone call between the two of you would make a big difference,” de Mistura said, addressing Russian President Vladimir Putin and Erdogan directly in a media briefing.

{articleGUID}

Moscow and Ankara should be given more time to negotiate a way to prevent an offensive, he added.

De Mistura, who has mediated several rounds of Syria talks in recent years, without making any progress, said he was “determined” to hold discussions with high-level envoys from Turkey, Iran and Russia on Tuesday and Wednesday of next week, despite concerns the offensive may begin before then.

The UN has previously warned that an all-out assault on Idlib could lead to a humanitarian catastrophe on a scale not yet seen in Syria’s conflict.

Meanwhile, US President Donald Trump late on Monday warned Syria against “recklessly” attacking Idlib, which he said could trigger a “human tragedy”.