"And how do you know who is fleeing?"
The key suspects are already under surveillance--you don't do raids without serious intel as to the target.
What we're looking for is who THOSE guys make contact with.
And why wouldn't they just use children to pass on messages to get out of Dodge?
"Jimmy, sweetie can you please bring these bags of pita bread over to your Aunt? Tell her that these were made with all my love and to enjoy each and every one." There goes little Jimmy delivering a message and there goes Uncle Ben to the bus stop on his way to work via his Uncle Tommy in Jordan.