Они, смутившись и испугавшись, подумали, что видят духа.
They were startled and frightened, thinking they saw a ghost.
But they were startled and frightened and thought they saw a spirit.
But they were startled and frightened and thought that they were seeing a spirit.
But the whole group was startled and frightened, thinking they were seeing a ghost!
But they were terrified and affrighted, and supposed that they had seen a spirit.
But they were terrified and frightened, and supposed they had seen a spirit.
But they, being confounded and being frightened, supposed they beheld a spirit.