Police examine CCTV footage of Derby stabbings
Police are examining CCTV filmed around the time of a street "altercation" in which four men were stabbed.
Two groups of people are thought to have clashed in Derby city centre in the early hours of Saturday.
A knife was recovered from the scene and three of the four men who were stabbed needed taking to hospital.
A 17-year-old boy and two men, aged 22 and 30, have been arrested over the incident, which happened in Curzon Street at about 04:30 BST.
The people arrested have all been released on bail.
The stabbed men's injuries were not life threatening and they have since been released from hospital.
The fourth man was treated at the scene.