Britney Spears is carried on a stretcher to a waiting ambulance from her Beverly Hills home late Thursday night Jan. 3, 2008.

Britney Spears opened a new chapter in her intoxicated life when she was whisked away in an ambulance after police were called to her house to help end a nearly three-hour custody standoff involving her young sons. NY Daily reports:

Officers were called to Spears' house around 8 p.m. to respond to the custody dispute with ex-husband Kevin Federline over their sons, 2-year-old Sean Preston and 1-year-old Jayden James, Lee said.

By about 10:30 p.m., six police cars, two ambulances and a fire truck had entered the gated-community that includes Spears' house. Several police cars were seen in the area earlier in the night. Spears turned over the children around 10:50 p.m., Lee said.

The 26-year-old pop star was taken to Cedars-Sinai Medical Center, Entertainment Tonight reported on its Web site Friday. Cedars spokeswoman Simi Singer said she could neither confirm nor deny the report, citing patient confidentiality laws. Officer Jason Lee of the Los Angeles Police Department told City News Service that Spears appeared to be under the influence of an unknown substance. He declined to elaborate. No injuries were reported.

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UPDATE: Insider Online reports:

BRITNEY SPEARS is under mental evaluation and has been placed under 72-hour lockdown at Cedars-Sinai hospital in L.A. after police were called to her house Thursday night. The pop star allegedly locked herself in a room with one of her young sons and refused to hand him over to her ex-husband KEVIN FEDERLINE.

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Stay tuned as the story develops.