ESV: But they were startled and frightened and thought they saw a spirit.
NIV: They were startled and frightened, thinking they saw a ghost.
NASB: But they were startled and frightened, and thought that they were looking at a spirit.
CSB: But they were startled and terrified and thought they were seeing a ghost.
NLT: But the whole group was startled and frightened, thinking they were seeing a ghost!
KJV: But they were terrified and affrighted, and supposed that they had seen a spirit.
NKJV: But they were terrified and frightened, and supposed they had seen a spirit.