A 47-year-old woman was arrested on suspicion of possession of an offensive weapon and assault, police said. Investigators believe the stabbing was mental health-related incident. A pair of scissors were recovered at the scene.

The current condition of the victims has not been released. Police remain at the scene.

The London Ambulance Service said an ambulance crew, a paramedic in a fast response car and an incident response officer had rushed to the scene and treated the four men before transporting them to a major trauma centre by road.

However, the ambulance service also dispatched London’s air ambulance. Video posted on social media shows a red helicopter making a dramatic landing in the middle of a crowded Trafalgur Square.

A 47-year-old woman was arrested on suspicion of possession of an offensive weapon and assault, police said. Investigators believe the stabbing was mental health-related incident. A pair of scissors were recovered at the scene.

The current condition of the victims has not been released. Police remain at the scene.