UPDATE: Britney Was Holding Her Kids Hostage!?

Entertainmentwise has learned that police were called to Britney Spears’ Beverly Hills home after the singer refused to hand her boys over to ex-husband Kevin Federline after their scheduled visitation.

Drama erupted after K-Fed’s bodyguards arrived at Brit’s home to collect Sean Preston, two, and one-year-old Jayden James at the arranged time of 7pm.

When Britney refused to co-operate, the police were called.

The pop wreck’s soon-to-be ex-attorney Sorrell Trope explained to Us mag: "In a normal case when someone shows up with a certified court order saying the kids need to be somewhere else, the police see to it that the order is obeyed. But that is in a normal case."

The LAPD confirms that they received the call at 8pm (PT) yesterday evening but would not reveal who made the call or its precise nature.

The boys were eventually returned to their father just before 11pm (PT), reports TMZ.

A smiling Brit – said to be under the influence of an "unknown substance” – was taken by ambulance to L.A.’s Cedars-Sinai Medical Center for what is being described as a “mental evaluation.” 

What took so long?

Cameras caught Brit as she was stretchered into the emergency room - click here to see the dramatic footage.