The families of three London schoolgirls thought to be in Syria have travelled to Turkey to retrace their steps. School friends Shamima Begum, 15, Kadiza Sultana, 16, and Amira Abase, 15, left east London for Turkey last month before crossing into an ISIS-controlled area of Syria. The Bethnal Green Academy pupils are feared to have reached the conflict zone to become so-called 'jihadi brides' with ISIS. Scroll down for video . Anguish: The families of three missing London schoolgirls have travelled to Turkey to retrace their steps . Questions: The families hope to find clues that may help them find or even contact their daughters . Emotional: The families went to the Istanbul coach station where the teenagers boarded their bus to Syria . On the journey, their families went first to the Istanbul coach station where the teenagers waited 18 hours in the biting February chill for their bus to the Syrian border. There they spoke to a man who unknowingly let the girls in. He told ITV News they were 'smiling as they arrived' and 'smiling as they left'. Renu Begum, sister of Shamima, told ITV News: 'This is our next step basically to get the message out to them that we've followed them all the way out here. We want them to know that we love them.' Halima Khanom, sister of Kadiza, said: 'I don't really recognise my sister, the video and the CCTV that we saw. Because this is just not her and we just want to understand her, you know, to find some answers and get some help.' Abase Hussein, father of Amira, said: 'I don't know how to explain. I can't describe my feelings. I feel like my girl is next to me when I find someone that's on their last journey who saw them. I feel like my daughter is next to me - that's the feelings I have.' Searching for clues: At the bus station, the family spoke to a man who unknowingly let the three girls in . Tears: The families struggle to hide their emotions as they retraced the steps of the London schoolgirls . The families left through the same door as the girls at the bus station, and family lawyer Tasnime Akunjee said: 'Of course they feel responsible for their own children, that goes without saying. 'But the fact is these girls were school children and much of what took place clearly took place at school. Police put a cap on information that they and the school were giving back to the parents.' The east London schoolgirls flew to Istanbul from Gatwick with Turkish Airlines and now believed to be in based in the Syrian town of Raqqa – the Islamic State's self-declared capital. Last week it emerged that Sharmeena Begum, 15, a close friend of the trio and a fellow pupil at Bethnal Green Academy, left Britain before them in December. There are suspicions the trio kept in touch with Sharmeena who passed on information about how to follow in her footsteps. Those closest to all four girls suspect they were groomed by Islamists using social networking sites and secretive internet messaging software. The families have criticised police and others for failing to stop them. But their plight has raised questions about why the families themselves did not spot their conversion to radical Islam. Scotland Yard chief Sir Bernard Hogan-Howe has said the three schoolgirls would not face prosecution if they returned home. Familiar route: The families, along with ITV's Rohit Kachroo, flew in to Istanbul from Gatwick . Looking for answers: By retracing the route of the schoolgirls, the families hope it might bring them home . Elsewhere last week, three British teenage jihadists were placed in custody after a dramatic security operation prevented them joining ISIS in Syria. A pair of 17-year-old schoolboys and a 19-year-old man, all from North-West London, were intercepted in Turkey after their parents realised they had fled to join the terrorist group. They dialled 999 and British police quickly tipped off their Turkish counterparts. Officials swooped on the group within minutes of their flight touching down in Istanbul. Security services say 600 British Muslims have gone to fight in Syria and around 60 of them are young women. They include 22 women and girls who have travelled in the past 12 months, many of whom wanted to become 'jihadi brides'. ISIS currently controls a swath of land slightly larger than the UK, from Aleppo to central Iraq, and has attracted thousands of foreign fighters to its cause. Turkey has faced criticism for not controlling its border with Syria, but has accused European states of failing to prevent would-be jihadists from leaving in the first place.
Shamima Begum, 15, Kadiza Sultana, 16, and Amira Abase, 15, in Syria . Left east London for Turkey then went into ISIS-controlled part of Syria . Feared to have gone to conflict zone to become 'jihadi brides' with ISIS . Families have retracted their steps to find clues or even contact with girls . They have previously criticised police and others for not stopping them .