Berean Standard Bible (BSB)
But they were startled and frightened, thinking they had seen a spirit.
World English Bible (WEB)
But they were terrified and filled with fear, and supposed that they had seen a spirit.
Strong's King James
But{G1161} they were terrified{G4422}{(G5685)} and{G2532} affrighted{G1719}{G1096}{(G5637)}, and supposed{G1380}{(G5707)} that they had seen{G2334}{(G5721)} a spirit{G4151}.
The F.O.G *
(37) But they were terrified and became fearful thinking they saw a ruach-spirit.
The F.O.G Message *
Young's Literal Translation
and being amazed, and becoming affrighted, they were thinking themselves to see a spirit.