Britney Spears was rushed to a Los Angeles Hospital late last night after the police responded to a call "about a custodial dispute regarding Britney Spears's children" and found her under the influence of an unknown substance.

People.com reports:

Britney Spears has been taken to a Los Angeles hospital for "an evaluation" after police were called to her Studio City home for a "custodial dispute" Thursday.

At around 8 p.m. police responded to a call "about a custodial dispute regarding Britney Spears's children," said LAPD officer Jason Lee.

Nearly three hours later, police determined that a court order stated that the singer's children, who were with Spears at the time, were supposed to be with Kevin Federline, and a transfer was arranged, according to Lee.

"While officers were on the scene, they observed Ms. Spears under the influence of an unknown substance," Lee added. "She is now being taken in for an evaluation, more than likely to a hospital. There were no reported injuries to anyone involved including the children."