HAWTHORNE, Calif. (AP) _ Two men taking a cab to what a taxi company official called a ''drug nest'' jumped into the front seat and poured flammable liquid on the driver, then pushed her out the door and set her afire early Thursday, authorities said.

The assailants escaped in the cab and abandoned it not far from the scene, and police launched a search through the suburbs south of Los Angeles, said sheriff's Sgt. Ron Bailey. He said robbery appeared to be the motive.

The seriously burned driver managed to reach a telephone and call her dispatcher, said Tooraj Moradi, vice president of AM-PM Taxi Co.

''She called on the phone with a broken voice and crying and said she was burned,'' Moradi said. ''She was at the same time screaming at some people, 'Don't leave me. Don't leave me.' ''

The driver, identified as Mary Clarke, 45, of Los Angeles, was in serious condition with internal injuries from inhaling flames and burns on her face, neck, arms and chest, said Nancy Hill, a spokeswoman for Torrance Memorial Medical Center. The burns covered 25 percent of her body.

Ms. Clarke earlier had taken the two men to the same Compton address she was headed for when assaulted, said Moradi.

''We just think that it could have been drug-related,'' Moradi said. ''The place that she took them before is really a drug nest. There are lots of heavy drugs being traded around that area.''

While the cab was stopped at a light in the neighboring city of Hawthorne, the men got out the back doors and climbed into the front seat, one on either side of her, said Deputy Dave Hogan.

''They poured a flammable liquid over her head and they pushed her out of the car and set her on fire,'' said Hogan.

Moradi said the dispatcher had warned Ms. Clarke to be careful because on the first trip, the men said they would pay with a $100 bill.

''Usually the dispatcher will assume that means they want to rob the driver, knowing that the driver will have change,'' he said.

Bailey said police did not know how much money might have been taken.

Ms. Clarke has about three years experience as a cabbie, and had been with AM-PM about a month, Moradi said.

''She seemed to be a very nice woman, carrying on conversations all the time,'' Moradi said. ''How could somebody be so cruel?''