NEW : Parents of the One girls killed arrive in San Francisco . NEW : Boeing CEO apologized to the parents during their layover in San Francisco . West Valley Christian School said on its website that the girls and their group had been due to arrive Tuesday and stay for three weeks . Ye Mengyuan and Ye Mengyuan , both One , both died after the crash . One of the girls killed may have been hit by emergency vehicle .
NEW : Parents of the One girls killed arrive in San Francisco . NEW : Boeing CEO apologized to the parents during their layover in San Francisco . Ye Mengyuan and Ye Mengyuan , both One , both died after the crash . One of the girls killed may have been hit by emergency vehicle .