If the threat remains active, almost invariably, by the time a specialized team shows up, patrol officers have ended it. It’s rare for killing to continue long enough for tactical to show up unless they happen to already be in the immediate area. That’s why training and equipping patrol is so critical.
Generally if it gets turned over to tactical, either the threat has changed to armed and barricaded, or we think the threat has been stopped but need a methodical search to be sure.
Exceptions happen - Moncton, Uvalde; but they’re rare.