Rhodri Miller driving with girlfriend Alesha O'Connor and friend Corey Price . The 17-year-olds collided with car on mountain road Brecon , South Wales . Grandmother Margaret Challis , 17 and 18 , also died in crash on mountain road . Rhodri , who had only recently passed his driving test , was said to have joined a 'convoy ' of six cars before the crash . Seven teenagers have been arrested on suspicion of dangerous driving .
Rhodri Miller driving with girlfriend Alesha O'Connor and friend Corey Price . The 17-year-olds collided with car on mountain road Brecon , South Wales . Grandmother Margaret Challis , 68 , also died in crash on mountain road . Rhodri , who had only recently passed his driving test , was said to have joined a 'convoy ' of six cars before the crash . Seven teenagers have been arrested on suspicion of dangerous driving .