SAN FRANCISCO -- A young man was fighting for his life after being struck by a car Thursday afternoon, just two days after two separate fatal collisions involving pedestrians in the city.

Police responded to Bush and Leavenworth streets around 5 p.m. for a traffic collision.

When officers arrived, they found that a car had struck a pedestrian, described as a man in his 20s.

The pedestrian was transported to San Francisco General Hospital, where he was listed in serious condition. Police said his injuries were considered life-threatening.

The driver remained at the scene, and an investigation is underway.

On New Year's Eve, two people were killed after being struck by vehicles in separate incidents. In one incident, a 6-year-old girl was killed by a driver who was charged with vehicular manslaughter with gross negligence and failure to yield to pedestrians in a crosswalk; officials later confirmed that he was registered as a driver for the Uber ride-sharing service, although he was not on duty for the company at the time of the crash.

Follow Katie Nelson at Twitter.com/katienelson210.