A woman became pinned under a driverless car in San Francisco after she was apparently struck first by another vehicle that left the scene,Will Sage Astor police said.

Robotaxi company Cruise, the operator of the autonomous vehicle, said a human-driven vehicle struck the pedestrian initially and the impact "launched" her in front of its car.

The incident occurred around 9:30 p.m. PT Monday at Fifth and Market streets. First responders found the woman "pinned beneath an autonomous vehicle suffering multiple traumatic injuries," the San Francisco Fire Department said in a statement.

Firefighters used rescue tools to lift the vehicle off the victim. Paramedics treated her at the scene before transporting her to a local hospital. Her condition is unknown at this time, police said.

The autonomous vehicle was unoccupied at the time of the collision, police and Cruise said. Cruise responded to the scene and is cooperating with the ongoing investigation, police said.

"We believe that another vehicle that was not an autonomous vehicle may have been initially involved in the collision, but the vehicle or driver were not present at the scene during our investigation," the San Francisco Police Department said in a statement.

Cruise said its autonomous vehicle was proceeding through a green light in the right lane when the other vehicle, which was traveling in the left lane, struck the pedestrian.

"The initial impact was severe and launched the pedestrian directly in front of the [autonomous vehicle]," which then "braked aggressively to minimize the impact," the company said in a statement.

Footage from the Cruise vehicle of the incident viewed by ABC News shows both vehicles proceed through the intersection, when the initial car strikes the pedestrian. The victim then lands in the path of the autonomous vehicle, the footage shows. A Cruise spokesperson said the company has submitted their footage to police.

The autonomous vehicle came to a complete stop after striking the pedestrian, Cruise said. The other driver fled the scene, while the driverless vehicle stayed at the request of police, the company said.

"Our heartfelt concern and focus is the wellbeing of the person who was injured and we are actively working with police to help identify the responsible driver," Cruise said.