Why does it say "Hagidu"?
Radak: Tell his Nevu'ah to the listeners, that each will tell his friend that Melech Bavel will come against them due to their evil deeds.
Malbim: This illustrates how the enemy will come suddenly to Tziyon, before it can prepare for war. They will tell in Yehudah, and immediately it will be heard in Yerushalayim, the capitol. In a normal war, word goes from the capitol to the Medinah!
Why should they blow the Shofar?
Rashi: Warn the residents to blow the Shofar to flee.
Radak: This will publicize [that Melech Bavel will come] more than repeating the Nevu'ah.
Malbim: It is to call people to go to the battlefield to greet the enemy.
What is the meaning of "Mal'u"?
Rashi: It is gathering. We find like this - "Asher Yikarei Alav Melo Ro'im" (Yeshayah 31:4), "Kar'u Acharecha Malei" (below, 12:6), "Yachad Alai Yismala'un" (Iyov 16:10). Radak - they should gather to the fortified cities or to Yerushalayim.
Malbim: While calling people to go to greet the enemy, they will complete the message (retract) and say not to greet them, for the enemy is too strong. Rather, gather to the fortified cities. And amidst saying this, they changed the announcement; refer to 4:6:1:1.
Will they be saved in the fortified cities?
Radak #1: Also they will be captured, but they will be saved for a short time.
Radak #2: The Navi addresses them according to their intent, that they will be saved.
