Pop-singer-turned-tabloid-queen Britney Spears [ tickets ] reportedly was hospitalized last night after police responding to a report of a dispute at her home deemed her to be under the influence of an unknown substance.

According to published reports, Spears' latest incident began when an unidentified person phoned the Los Angeles Police Department at around 8 p.m. last night to report a domestic disturbance. The alleged row began when Spears--who is in the midst of a legal battle with ex-husband Kevin Federline to determine custody of the couple's two sons (2-year-old Sean Preston and 1-year-old Jayden James), and was apparently due to have the children from 12 p.m. to 7 p.m. yesterday--reportedly refused to turn the boys over to Federline's bodyguards when they arrived at her home to pick up the children.

Officers responded to Spears' home, and reportedly were there until Spears turned over the children at around 10:50 p.m.

According to the Associated Press, six police cars, an ambulance and a fire truck entered Spears' gated community at around 10:30 p.m., and Spears was subsequently seen being lifted in a gurney onto the ambulance, which transported her to an unidentified Los Angeles hospital where she was still being evaluated as of earlier today, according to reports.

Police spokesperson Jason Lee was quoted by the City News Service as saying that Spears was under the influence of an unknown substance, and that no injuries were reported.

Earlier in the day, Spears reportedly showed up an hour and 45-minutes late for a deposition in connection with the custody dispute, and was subsequently deposed for 14 minutes rather than the scheduled two hours, Federline's attorney told the AP.

"The deposition proceeding did go forward today," attorney Mark Vincent Kaplan was quoted as saying. "It was scheduled for 9:45 to 11:45. However, it wasn't able to commence until 11:32.

"You can imagine in 14 minutes there's not a lot of time to develop questions," added Kaplan, who reportedly said that another deposition would be scheduled.

Yesterday's deposition followed previously scheduled sessions for Dec. 12--for which Spears called in sick, but was photographed driving with a friend that same day--and Wednesday (1/2), for which Spears didn't show up, according to Kaplan.

Also on Wednesday, Spears' attorneys filed a court motion asking to be relieved from the case due to "a breakdown in communications" with Spears that makes representing her "impossible."

Spears and Federline wed in October of 2004, and divorced last July. Federline currently has temporary custody of the children because Spears has violated a number of court orders.