Emergency services were called to East Shore Way in Milton just after 8am today.
Police and paramedics were called to the scene.
A cordon still remains in place this afternoon.
A 30-year-old woman, a 27-year-old woman, both from Portsmouth, and a 30-year old woman from Brighton, have been arrested on suspicion of grievous bodily harm.
Police have also said a 30-year-old woman from Portsmouth has been arrested on suspicion of affray.
Here are our latest photos from the scene.