Four men and three women are in custody.
Scotland Yard said the arrests were made on “suspicion of various offences”.
Police were called to Prentis Road, South London, at 4.16pm on Thursday to reports of a stabbing.
Met Police have advised that officers remain at the scene and there are currently road closures along Prentis Road.
The public are advised to avoid the area.
A statement by the force said: “The investigation is in its very early stages and work to establish the circumstances continues.
“Anyone with any information is asked to call police on 101 quoting CAD 5897/10JUNE.”