Brit's Kids Are Safe, She's Under the Influence!

1/4/2008 4:26 AM PST BY TMZ STAFF
TMZ has learned Sean Preston and Jayden James were returned to K-Fed tonight just before 11:00 PM PT.

We're told that while cops were at the troubled pop star's home, they discovered Spears "under the influence of an unknown substance."

Several ambulances have been called to the scene.