Complex sentence: Horrified, they attempt to leave as Andoy arrive, startling them and nearly fell at the lighthouse until he catches them but the two ghosts are walking towards them, causing the girls and Andoy to fell at the lighthouse.
Split into simpler sentences: Horrified, they attempt to leave as Andoy arrive, startling them and nearly fell at the lighthouse before he catches them. When he attempt to pull them up, the two ghosts are walking towards them, causing the girls and Andoy to fell down the lighthouse.