Were opened (διηνοιχθησαν). Ingressive first aorist passive indicative of διανοιγω.

Knew (επεγνωσαν). Effective first aorist active indicative fully recognized him. Same word in verse Luke 24:16.

Vanished (αφαντος εγενετο). Became invisible or unmanifested. Αφαντος from α privative and φαινομα, to appear. Old word, only here in the N.T.