Tel Abyad was one of two border towns that saw some of the heaviest fighting when Ankara launched its cross-border offensive on October 9 targeting Kurdish YPG forces in northeast Syria. The YPG -- which Ankara considers a terrorist group because of its ties to PKK Kurdish militants in southeast Turkey -- had for years been allied to the United States in the fight against Islamic State. Turkey began the incursion after President Donald Trump pulled US troops out of the area. Saturday's blast caused extensive damage to a main street in Tel Abyad, sending thick smoke into the air above the wreckage, videos posted on social media showed. The Syrian Observatory for Human Rights, a British-based war monitor, said four civilians from the same family were among those killed by the explosion, which the local council said residents blamed on the YPG and PKK. Turkey's Defence Ministry also accused the YPG of carrying out the attack, which it said had killed three people and wounded 20, while a senior spokesman for the Kurdish-led Syrian Democratic Forces (SDF) accused 'Turkish-backed mercenaries' of being responsible. 'After expelling the majority of Kurds, looting almost all the shops and houses in this Kurdish district of Tel Abyad, Turkish-backed mercenaries are now attempting to displace the remaining Kurdish population from their homes by random explosions in civilian areas,' Mustafa Bali, the head of SDF's media office, said on Twitter. Similar car blasts frequently hit crowded civilian areas in the mainly Arab populated towns near the border with Turkey, which are under the control of Turkish-backed forces. The Kurdish-led forces say its fighters are engaged in a guerrilla campaign against Turkish forces but denies targeting civilians.