LONDON (AP) - London police are investigating a small explosion at a London Underground station.

Police said they are not aware of any serious injuries in what the force called a "minor explosion" at Southgate Tube station Tuesday evening.

Police said officers remain on the scene and are investigating.

British Transport Police say a "small number" of people were treated at the scene. The nature of the injuries was not immediately clear.

Police responded after people ran from the station and said there had been an explosion.

Police say no cause has yet been established.