The incident was reported at a bus stop near Olympic Boulevard and Flower Street around 1 a.m.
The victim was walking down the street when suddenly he crossed paths with the suspect who threw a liquid substance at him and used a lighter to set him on fire, police said. She immediately left the scene while witnesses rushed in to help the victim. He was rushed to the hospital by ambulance with what has been described as second and third-degree burns.
Investigators said the victim and the suspect did not know one another and witnesses added that the two did not exchange words prior to the attack.
Authorities described the suspect as a white woman with blond hair, around 40 years old, 5 feet 7 inches tall, weighing 125 pounds. She was last seen wearing a white hoodie and blue jeans.
Anyone with information is asked to contact the Los Angeles Police Department.