Actress Lindsay Lohan is pictured in this police booking photograph released July 24, 2007.[AP]

SANTA MONICA, Calif. - In the minutes before Lindsay Lohan's arrest, the mother of her former personal assistant called 911 and pleaded frantically for help because a mysterious car was following her — unaware that Lohan was behind the wheel, according to an audio copy released Thursday.

Lohan's personal assistant had quit hours before the event, according to police.

The woman apparently didn't realize that Lohan was in the vehicle following her when she contacted a Santa Monica police dispatcher shortly after 1:30 a.m. Tuesday while driving on Wilshire Boulevard.

"We were just about to park our car. We are turning home and out of nowhere a huge white GMC came up," the woman said to the dispatcher. The recording included unintelligible remarks apparently to the woman's passenger.

"We're being followed by a GMC ... the gentleman jumped out of the car," she added a few seconds later. "Oh my God, sir, they're following us. We need help."

During the nearly three-minute 911 call, the dispatcher repeatedly asked the woman where she is. The woman eventually said she was heading for the police station.

Police said the woman, accompanied by a passenger, drove her black Cadillac Escalade into the parking lot of Santa Monica's Civic Auditorium, about a block away from the police department, followed by Lohan driving a Yukon sport utility vehicle.

"There he is, that white GMC pickup," the dispatcher said to someone as the car appeared.

During the call, the woman could be heard saying "Oh my God, what is he doing?" Near the end, hysterical but muffled yelling and screaming is heard.

"They're in front of HQ now. Roll somebody code. Ma'am, what's going on there? Hello? Hello? Ma'am? Hello?" the dispatcher said.

A few moments later, a police unit showed up and the woman could be heard in the background, apparently pointing out people to the officers.

"That's him, that's him right there," she said. "And him, stop them."

Authorities who arrived saw Lohan and the woman in what police have called a "heated debate." They also said two men were with Lohan in the car.

Lohan was arrested for investigation of misdemeanor driving under the influence and with a suspended license, and felony cocaine possession.