Ezekiel Chapter 9, verses 2-6

2 And behold six men came from the way of the upper gate, which looketh to the north: and each one had his weapon of destruction in his hand: and there was one man in the midst of them clothed with linen, with a writer's inkhorn at his reins: and they went in, and stood by the brazen altar.

3 And the glory of the Lord of Israel went up from the cherub, upon which he was, to the threshold of the house: and he called to the man that was clothed with linen, and had a writer's inkhorn at his loins.

4 And the Lord said to him: Go through the midst of the city, through the midst of Jerusalem: and mark Thau upon the foreheads of the men that sigh, and mourn for all the abominations that are committed in the midst thereof.

5 And to the others he said in my hearing: Go ye after him through the city, and strike: let not your eyes spare, nor be ye moved with pity.

6 Utterly destroy old and young, maidens, children and women: but upon whomsoever you shall see Thau, kill him not, and begin ye at my sanctuary. So they began at the ancient men who mere before the house.