How would police go about getting a sniper out of a abandoned factory/warehouse?

Say there is a sniper barricaded in an abandoned factory or warehouse, and and a buddy of his, making sure nobody gets in the room with him with an Ar15 or semi auto .22.

The sniper is targeting civilians and police, from the 7th floor of the building. How would police/SWAT/ATF get them out?
Update: Boy boy boy, you guys are so stupid, giving away info like this. So damn gullible. Good thing this isn't national security or I could probably get it out of you to.
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