“When he did come out,

Zechariah

Could not speak

To them.

They realized

That he had seen

A vision

In the sanctuary.

He kept motioning

To them.

However,

He remained

Unable to speak.”

ἐξελθὼν δὲ οὐκ ἐδύνατο λαλῆσαι αὐτοῖς, καὶ ἐπέγνωσαν ὅτι ὀπτασίαν ἑώρακεν ἐν τῷ ναῷ· καὶ αὐτὸς ἦν διανεύων αὐτοῖς, καὶ διέμενεν κωφός.

Luke indicated that the people praying in the Temple, outside the sanctuary, were surprised when Zechariah finally came out (ἐξελθὼν δὲ) of the sanctuary.  They saw that Zechariah could not speak to them (οὐκ ἐδύνατο λαλῆσαι αὐτοῖς) or give his blessing.  They realized or recognized (καὶ ἐπέγνωσαν) that he had seen a vision or had a supernatural experience (ὅτι ὀπτασίαν ἑώρακεν) while he was in the sanctuary (ἐν τῷ ναῷ).  Zechariah kept motioning or making signs to them (καὶ αὐτὸς ἦν διανεύων αὐτοῖς).  However, he could not communicate with them, since he was unable to speak as he remained mute (καὶ διέμενεν κωφός).