Three soldiers were among those injured after a number of military horses broke loose and caused carnage in central London before being captured.
A British Army spokesperson said the soldiers were taken to hospital and that a fourth soldier was thrown from their horse but remained unharmed.
The London Ambulance Service said it treated four injured people in total and took four people to hospital after the incident. It is not clear who the fourth injured person was.
The animals, one of which appeared to be covered in blood, were seen running around Whitehall and Victoria, with two of the horses reaching as far as Limehouse and Shadwell.
Witnesses reported seeing a soldier falling to the ground, while an army spokesperson confirmed that a number of personnel and horses had been injured and were receiving medical attention.
Pictures and videos of the horses were shared on social media, with a black horse colliding into a taxi and another smashing the windscreen of a double-decker bus.
The animals, which form part of the Household Cavalry, are understood to have become spooked during their daily morning exercise.