LONDON — Four people were injured Wednesday in a collision involving a taxi and pedestrians in London’s busy Covent Garden tourist hub.

The city’s Metropolitan Police force said the collision was thought to be a routine, if serious traffic accident; it tweeted that the incident was “not terror related.”

Witnesses reported on Twitter that one of London’s iconic black cabs mounted a sidewalk in Covent Garden, a shopping and entertainment area in the West End theater district. Police said the taxi driver stopped at the scene and had been detained.

The London Ambulance Service said four people were injured, including a man hospitalized with a serious leg injury. It said two others were treated for minor injuries and also taken to hospitals, and a fourth person was treated at the scene.

The Transport for London transportation authority said several roads were closed “due to a serious collision.”

The Covent Garden area — full of shops, restaurants and a busy market — is one of London’s most popular tourist spots.