"As I listened, he said to the others, 'Follow him through the city and kill, without showing pity or compassion. Slaughter the old men, the young men and women, the mothers and children, but do not touch anyone who has the mark. Begin at my sanctuary.' So they began with the old men who were in front of the temple." NIV translation
We see that God instructs the angels to execute His judgment on all who do not have His mark on them. This mark and the angel who puts it on the remnant is a picture of Jesus covering those that accept Him with His blood. We see that the judgment includes all people and begins at the temple.
"Then he said to them, 'Defile the temple and fill the courts with the slain. Go!' So they went out and began killing throughout the city." NIV translation
Is God really telling them to "defile the temple"? The short answer is yes but we must remember that it was already defiled by the fact that it had become a place of idolatry. As we saw before, God's presence was prepared to leave the temple.
"While they were killing and I was left alone, I fell facedown, crying out, 'Alas, Sovereign Lord! Are you going to destroy the entire remnant of Israel in this outpouring of your wrath on Jerusalem?' He answered me, 'The sin of the people of Israel and Judah is exceedingly great; the land is full of bloodshed and the city is full of injustice. They say, "The Lord has forsaken the land; the Lord does not see." So I will not look on them with pity or spare them, but I will bring down on their heads what they have done.'" NIV translation
A true prophet has a broken heart when he sees people being judged and Ezekiel fell down and cried out to God for the people. Their sin is described as "exceedingly great" and this is talking about the fact that, once they turned their backs on God, there was no alternative to punishing them. The people had rejected God and so they were going to be covered in their own blood.
"Then the man in linen with the writing kit at his side brought back word, saying, 'I have done as you commanded.'" NIV translation
In this verse we see the fact that, God will withhold His judgment until His people are sealed but, after that, it is unstoppable.