A woman suffered head injuries and another suffered cuts to her face during an incident in Kettering on Saturday evening.
Police were called to the scene, at the corner of Montagu Street and Tresham Street at about 8pm.
A spokesman for the force said officers were called to reports of a fracas in the street.
When they arrived, one woman had suffered minor injuries to her face and the other had head injuries.
The air ambulance airlifted the woman with head injuries to hospital, but the injury was said to be not as serious as first thought.
The spokesman added: “We are speaking to both women. The incident is still under investigation.”
Rumours circulating on social media said the incident had been a stabbing, but Northamptonshire Police said this was not the case.