A taxi plowed into multiple people after it hopped a curb in a popular tourist area of Manhattan, sending three pedestrians to the hospital -- including a young boy and his mother visiting from another country, according to sources

The cab was heading west on 34th Street just after 4 p.m. on Christmas when it veered onto the sidewalk at Sixth Avenue near Herald Square, police said.

At least six people were struck by the taxi, according to law enforcement sources. Three people -- a 9-year-old boy, a 41-year-old woman and a 49-year-old woman -- were taken to the hospital; their conditions were not immediately clear, but all three were expected to survive. Three others refused medical attention at the scene.

The boy and mother hit by the cab were visiting New York City from Australia, law enforcement sources told NBC New York.

It was not known what led to the cab going onto the sidewalk, but sources said the 58-year-old driver may have suffered a medical episode. No charges had been filed.

An investigation into the crash is ongoing.