Officers were called at 8 p.m. and were still at the house two hours later, said Officer Jason Lee, a police spokesman.
The call involved a "family custodial dispute that we are trying to resolve ... peacefully by court order," Lee said, declining to elaborate.
Spears and ex-husband Kevin Federline are fighting over custody of their sons, 2-year-old Sean Preston and 1-year-old Jayden James.
Federline, 29, has temporary custody of the children because Spears, who has limited visitation rights, has defied court orders. The two were married in October 2004 and divorced in July.
Calls to attorneys for Federline and Spears were not immediately returned.
Earlier Thursday, the 26-year-old singer appeared for a deposition in the custody dispute.
She was deposed for just 14 minutes, attorney Mark Vincent Kaplan told reporters after she left.
Spears called in sick for a Dec. 12 court-ordered deposition, but was photographed that day driving with a friend. She also didn't show up for a session Wednesday, Kaplan said.
Spears' attorneys from the firm Trope and Trope on Wednesday filed a court motion asking to be relieved due to a "breakdown" in communication with their client.
Kaplan said Spears' attorneys were present for what became a very abbreviated session.
"The deposition proceeding did go forward today. It was scheduled for 9:45 to 11:45," Kaplan said. "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," he said.
Kaplan said another deposition will be scheduled.
City News Service contributed to this report.