Albert Barnes Commentary Ezekiel 5:2

"A third part shalt thou burn in the fire in the midst of the city, when the days of the siege are fulfilled; and thou shalt take a third part, and smite with the sword round about it; and a third part thou shalt scatter to the wind, and I will draw out a sword after them." — Ezekiel 5:2 (ASV)

“The third part burnt in the middle of the city” represents those who perished within the city during the siege; “the third part struck down around it” (the city) “with” the sword, those who were killed around the city during the same period; “the third part scattered to the wind” those who after the siege were dispersed in foreign lands.

In the middle of the city - The prophet is in exile, and is to do this in the middle of Jerusalem. His action, being ideal, is fittingly assigned to the place which the prophecy concerns.

When the days of the siege are fulfilled - that is, “when the days of the figurative representation of the siege are fulfilled.”