And he vanished out of their sight (αὐτὸς ἄφαντος ἐγένετο ἀπ' αὐτῶν)
Lit., he, invisible, became away from them. It is not simply, he suddenly departed from them, but he passed away from them invisibly. The ἐγένετο, became, is construed with ἀπ' αὐτῶν, from them.