A police officer is understood to have been stabbed in the hand as he tackled a crime in Northampton.
Witnesses described seeing 60 or more officers descend on Hardlands Road, Duston on Monday evening.
Residents were told that a male police officer, who had been called out to a disturbance, had been stabbed.
A man was arrested at the scene.
Superintendent Chris Hillery said: “Police were called to an incident in Hardlands Road, Duston, at about 6.30pm yesterday evening (Monday, 4 July), during which a police officer was assaulted.
“The officer received stab wounds to his hand and was taken to Northampton General Hospital for treatment.
“A 47-year-old-man was arrested and is currently in police custody.”
Speaking at a Police and Crime Panel meeting today, Northamptonshire’s Police and Crime Commissioner Stephen Mold said the officer had been stabbed at the end of the incident.
Mr Mold said the officer was trying to stop a man self-harming himself when he got stabbed in the hand.