She said he grabbed her from behind, but she was able to get away, while he ran back to his vehicle.
The suspect was described as Hispanic, in his 40s, about 200 pounds with brown eyes.
As he drove off, the victim noticed a second suspect in the passenger seat, who was described as Hispanic, in his 40s with short brown hair and a mole under his right eye.
The victim also said the back doors of the van were open.
Anyone with information is urged to call the South Pasadena Police Department at (626) 403-7280.