The bomb packed into a car exploded with deafening noise, spraying shards of metal and glass through the air and gouging a crater into the road. The victims were families who had gone out in the winter sunshine on Sunday and young children were among the 15 dead and wounded.

This was the first suicide bombing in al-Rai since the town was recaptured from Isis by Syrian opposition fighters and the Turkish military. It took place two days after the Islamist terrorists had fired missiles into the same area spreading, came the panicked claimed, poisonous chemical gas.

Tests carried out by Turkish doctors and scientists in Killis across the Turkish border on those affected failed to find any chemical traces, but evidence, instead, of a “tear gas like substance” which caused temporary illness. The injuries from the bomb were much more severe, with some of those treated at the local hospital not expected to survive.

Kurds capture Isis fighter

The attacks, less than a mile from the Turkish frontier, are in reaction to what is unfolding 30 miles to the north. Three forces which have been engaged in a bitter struggle against each other in Syria’s civil war are closing in on a city which is a strategic prize for an offensive on Raqqa, the capital of the caliphate proclaimed by Isis.

Rebel Sunni Arab fighters of the FSA ( Free Syrian Army) with Turkish military backing; A Kudish led alliance with American advisors and air support and the regime’s army with Russian backing are closing in on al-Bab in Aleppo Province, fighting each other as well as Isis on the way.

Al-Bab, or The Gate, is the last remaining significant stronghold left for Isis before Raqqa and unlocking the hold of the Islamists on the city and the routes along it is viewed as essential in launching the final campaign against the group and the killing or capturing of its leaders.

What happens in al-Bab will not only have a major bearing on the future of Raqqa, but also events in Aleppo and the aftermath of the operations there as the Assad regime carries out a push to take the rebel held east of the city.

Al-Bab supplied the largest contingent of fighters during the battle for Aleppo in 2012 and was subsequently in the forefront in the struggle against Jabhat al-Nusra, the al-Qaeda affiliate in Syria and Isis. Recep Tayyip Erdogan has publicly declared that he wants the rebels his government is supporting with a 10,000 strong Turkish force, “Operation Euphrates Shield”, to move to the city. Gaining possession would not only provide a natural defence point for the 5,000 square kilometre “security zone” Ankara wants to establish, but act as a check on expansion of regime forces if and when they take Aleppo.

In pictures: Turkey launches operation in Syria Show all 9 1 /9 In pictures: Turkey launches operation in Syria In pictures: Turkey launches operation in Syria Turkish tanks driving to the Syrian-Turkish border town of Jarabulus yesterday AFP/Getty In pictures: Turkey launches operation in Syria Turkish-backed gather on the outskirts of Jarabulus, Syria, ahead of an offensive on 24 August 2016 Reuters In pictures: Turkey launches operation in Syria Turkish army tanks make their way towards the Syrian border town of Jarabulus, Syria August 24, 2016 Reuters In pictures: Turkey launches operation in Syria Turkish soldiers return from Syria to Turkey with tanks after a military operation at the Syrian border as part of their offensive against the Islamic State (IS) militant group in Syria, Karkamis district of Gaziantep, Turkey, 25 August 2016 EPA In pictures: Turkey launches operation in Syria Turkish army tanks and Turkey-backed Syrian opposition forces move toward the Syrian border as pictured from Karkamis, Turkey, AP In pictures: Turkey launches operation in Syria Turkish tanks on their way to the Turkish-Syria border during an operation against Isis on 24 August 2016 EPA In pictures: Turkey launches operation in Syria Syrian opposition fighters being transported during preparations to enter Jarabulus in Karkamis, Turkey, on 24 August 2016. EPA In pictures: Turkey launches operation in Syria An air strike hitting Isis-controlled territory near Jarabulus, near the Turkish border, on 24 August 2016. EPA In pictures: Turkey launches operation in Syria A Turkish army tank and an armoured vehicle stationed near the border with Syria. Turkish media reports say Turkish artillery has launched new strikes at Isis targets across the border AP

Opposition fighters supported by Turkish armour and warplanes captured the villages of Umm Shukyaf, Umm Adshah and Anifiyah at the weekend, while at the same time launching attacks against the American backed Syrian Democratic Forces (SDF) in nearby Sab Wiran and Sheikh Nassir.

The results of the attacks were inconclusive and the SDF, led supposedly by the Kurdish militia YPG with Arab groups in the ranks, claimed to have destroyed a Turkish tank. Meanwhile the SDF continued its offensive, backed by US air strikes, against Isis, capturing the villages of Tal al-Jijan and Tal Unayb, west of al-Bab after prolonged and intense clashes.

Regime forces, while continuing its offensive to capture the eastern part of Aleppo from rebels, advanced towards al-Bab, taking the villages of Khirbat Duwayr, Amad Taltinah, Shaalah and Tal Al-Khashkhashat. Hizbullah and the pro-Damascus Kurdish group, Kafr as Saghir Martyrs, took part in the fighting. Turkish backed rebels maintain that the SDF provided fire support for the regime forces – more evidence, they insisted, to back their charge of collusion between Bashar al-Assad and the Kurds.

Boy asks if he will die after alleged chlorine attack in Aleppo

The complex and violent tapestry on the ground holds the increasing risk of outside players being sucked further into the conflict. President Erdogan called Vladimir Putin at the weekend after air strikes by Assad regime warplanes, had killed four Turkish soldiers and injured nine others near al-Bab. The two leaders, say Turkish officials, are in regular contact with each other over Syria, a process started by the rapprochement which the confrontation following the shooting down of a Russian plane by the Turks last year.

There seems little prospect, however, of the accusations and recriminations on the ground coming to an end. Motassim Khalid Abdullah, an officer with a Free Syrian Army (FSA) acting alongside Turkish troops in Syria spoke of his bitterness about the activities of the SDF. “They are Kurdish, YPG (a Kurdish militia) controlled. They say they are fighting Daesh (Isis) but they are also fighting us and it is for definite that they are helping Bashar when it suits them” he declared.

“We have proof that they were using their artillery when the regime advanced on al-Bab at Amad Taltinah and Shaalah. We are not saying they want Bashar to get al-Bab. They have already said they want al-Bab themselves. They want to create a Kurdistan out of Syria, Iraq and Turkey. The Turks know this and that is the reason they are in Syria. The Americans must also know this, but they keep on supporting the Kurds. It is some kind of a game the Americans are playing.”

US officials announced recently that the SDF would withdraw from Manbij, another town recently captured from Isis, leaving it to the FSA and Arab tribal militias. The Kurds, however, still maintain a presence there and have accelerated operations to gain territory nearby.